What was the gross profit for the second quarter of 2021 and what was the gross margin for the same period
ty consultants, the [Inaudible] generation prefers smart technology products and are more likely to demand and purchase Smart Home appliances.
Secondly, the development of new energy vehicles over the past two years has created an emotional connection between customers and the smart products and many other industries have also entered the intelligence era. Demand for smart products will drive the demand to Smart Home industry and related to an increase in consumer acceptance. Thirdly, China's 5G infrastructure has improved greatly over the past years. According to a report issued by the Ministry of Industry and Information Technology of Chinese Government, the personnel user penetration rate at 5G will exceed 40%, and the average annual growth rate of 5G units will actually 200% by 2023.
The ministry mentioned that Smart Life and Smart Home will be key parts in promoting IoT applications. Our national policy support will also benefit the development of the IoT Smart Home industry. We are committed to becoming the leading one-stop IoT home solutions provider, while developing our hardcore technology. Looking to the second half of the year, we will continue to improve our products through AI innovation is actually our larger store better merchant channel enhancement strategy and strengthen our trending technology branding.
With the ongoing development of Home Smart expansion in China, we remain confident in our ability to capitalize on opportunities and deliver long-term growth, as well as contribute positively to our consumer core life and industrywide intelligence transformation. So, this concludes our founder's remarks. Let's now turn to the detailed financial review of the second quarter of this year, as well as the outlook for the third quarter. Net revenues decreased slightly by 1.5% to RMB 1.66 billion from RMB 1.68 billion for the second quarter last year and increased by 43% compared to the same period of 2019.
The slight year-over-year decrease was primarily due to first sales decreases in water purifiers and smart appliances resulting from the product portfolio adjustments for margin expansion and second, a high base effect during the same period of last year due to promotional activities after COVID-19 pandemic pick. Revenues from IoT @ Home portfolio increased by 7.9% to RMB 1.16 billion from RMB 1.06 billion for the second quarter last year. The growth was primarily driven by sales increases in certain product series, particularly the Viomi-branded [Inaudible] and the washing machine. Selling from our home water solutions decreased by 18% to RMB 218.9 million from RMB 266.8 million for the second quarter of last year.
The decline was primarily due to a decrease in sales of Xiaomi-branded water purifiers resulting from a product portfolio adjustment, though partially mitigated by the sales increases in Viomi-branded water purifier. Due to the product portfolio adjustment in Xiaomi-branded water purifier, we achieved year-over-year and quarter-over-quarter increases in the overall gross margin of the home water solutions category. Revenues from consumables increased by 18.2% to RMB 102.2 million from RMB 86.4 million for the second quarter of 2020, primarily due to the increased demand for our water purifier filter products. Revenues from small appliances and others decreased by 28.8% to RMB 191.5 million from RMB 268.8 million for the second quarter of 2020, primarily due to continued portfolio optimization for higher gross margin in this category.
Gross profit increased by 46% to RMB 351.8 million and gross margin was 21.2%, compared to 14.3% for the second quarter last year. The year-over-year increase in gross margin was primarily driven by our efforts to shift the business and product mix toward higher gross margin products. And this includes the increased revenue contribution from sales of new Viomi-branded water purifier and super boxes more as cost control measures and margin optimization across our product lines. Total operating expenses increased by 29.4% to RMB 309.7 million, primarily due to the inc
ty consultants, the [Inaudible] generation prefers smart technology products and are more likely to demand and purchase Smart Home appliances.
Secondly, the development of new energy vehicles over the past two years has created an emotional connection between customers and the smart products and many other industries have also entered the intelligence era. Demand for smart products will drive the demand to Smart Home industry and related to an increase in consumer acceptance. Thirdly, China's 5G infrastructure has improved greatly over the past years. According to a report issued by the Ministry of Industry and Information Technology of Chinese Government, the personnel user penetration rate at 5G will exceed 40%, and the average annual growth rate of 5G units will actually 200% by 2023.
The ministry mentioned that Smart Life and Smart Home will be key parts in promoting IoT applications. Our national policy support will also benefit the development of the IoT Smart Home industry. We are committed to becoming the leading one-stop IoT home solutions provider, while developing our hardcore technology. Looking to the second half of the year, we will continue to improve our products through AI innovation is actually our larger store better merchant channel enhancement strategy and strengthen our trending technology branding.
With the ongoing development of Home Smart expansion in China, we remain confident in our ability to capitalize on opportunities and deliver long-term growth, as well as contribute positively to our consumer core life and industrywide intelligence transformation. So, this concludes our founder's remarks. Let's now turn to the detailed financial review of the second quarter of this year, as well as the outlook for the third quarter. Net revenues decreased slightly by 1.5% to RMB 1.66 billion from RMB 1.68 billion for the second quarter last year and increased by 43% compared to the same period of 2019.
 The slight year-over-year decrease was primarily due to first sales decreases in water purifiers and smart appliances resulting from the product portfolio adjustments for margin expansion and second, a high base effect during the same period of last year due to promotional activities after COVID-19 pandemic pick. Revenues from IoT @ Home portfolio increased by 7.9% to RMB 1.16 billion from RMB 1.06 billion for the second quarter last year. The growth was primarily driven by sales increases in certain product series, particularly the Viomi-branded [Inaudible] and the washing machine. Selling from our home water solutions decreased by 18% to RMB 218.9 million from RMB 266.8 million for the second quarter of last year.
The decline was primarily due to a decrease in sales of Xiaomi-branded water purifiers resulting from a product portfolio adjustment, though partially mitigated by the sales increases in Viomi-branded water purifier. Due to the product portfolio adjustment in Xiaomi-branded water purifier, we achieved year-over-year and quarter-over-quarter increases in the overall gross margin of the home water solutions category. Revenues from consumables increased by 18.2% to RMB 102.2 million from RMB 86.4 million for the second quarter of 2020, primarily due to the increased demand for our water purifier filter products. Revenues from small appliances and others decreased by 28.8% to RMB 191.5 million from RMB 268.8 million for the second quarter of 2020, primarily due to continued portfolio optimization for higher gross margin in this category.
Gross profit increased by 46% to RMB 351.8 million and gross margin was 21.2%, compared to 14.3% for the second quarter last year. The year-over-year increase in gross margin was primarily driven by our efforts to shift the business and product mix toward higher gross margin products. And this includes the increased revenue contribution from sales of new Viomi-branded water purifier and super boxes more as cost control measures and margin optimization across our product lines. Total operating expenses increased by 29.4% to RMB 309.7 million, primarily due to the inc