Johanna (Jo) Koster was a Dutch painter. In 1885, she went to the Rijksnormaalschool voor Tekenonderwijs in Amsterdam and in 1885 to the Academie in Rotterdam. In 1894, she travelled to Paris and later to Brussels, where she painted in the Neo-Impressionist and Pointillist style. She was a member of the artist associations Arti et Amicitiae, Pulchri Studio, Vereeniging Sint Lucas and Vereeniging van Beeldende Kunstenaars ‘De Rotterdammers’. Later in her life, she was active in Italy, France, Spain and Germany. Her work is to be found in the Rijksmuseum Amsterdam and the Kröller-Müller Museum.
