K.A.R. Bosscha was the son of renowned German-Dutch physicist Johannes Bosscha and Paulina Emilia Kerkhoven. After gaining some formal education in engineering at Polytechnical School of Delft, in 1887 came out to Netherlands Indies and stayed with his uncle while working at Sinagar Estate near Cibadak (West Java) that his uncle owned. Work at his uncle's company gave him little satisfaction, thus after six months he went to Sambas (Borneo) to join his older brother John Bosscha, a geologist.