kalou played in hertha's brief europa league stay against brøndby if, as well as their first round pokal match against jahn regensburg, but did not feature in the bundesliga initially for pál dárdai. an injury to vladimír darida vacated a spot initially for valentin stocker, but when stocker picked up a three-match ban for a straight red card at borussia dortmund, it was kalou who filled the hole in the attacking midfield, making his season debut on 22 october against fc köln. on 4 november, kalou emphatically ended his scoreless start to the season, picking up a hat trick against borussia mönchengladbach in a 3–0 victory, moving his side temporarily into third place. on 15 march 2017, kalou signed a contract extension at hertha, keeping him at the olympiastadion until 2019, with kalou adding "i'm really happy in berlin and still have a lot to achieve with hertha. i want to help build on the progress the team has made in recent years."