Three novel species of Bacillariophyta (diatom) are described from the sediments of Paleolake Lorenyang, a large lake that existed in the Turkana Basin, Kenya during the Gelasian age of the Pleistocene Epoch. Sediment cores extracted as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) were sampled to provide a diatom-based paleoecological record of Paleolake Lorenyang. Preliminary results of the paleoecological analysis unearthed three novel species of diatoms belonging to Surirella and Thalassiosira in the Natoo Member of the Nachukui Formation. Comparisons of Surirella from Paleolake Lorenyang are made to previous reports of Surirella from modern lakes in East Africa and comparisons of Thalassiosira species from the paleolake are made to modern and fossil species reported from East Africa. This is a first report of diatoms in the Natoo Member, which has previously been described as a floodplain deposit, and thus provides evidence of the last occurrence of Paleolake Lorenyang within the Turkana Basin. Herein we describe a new species of Surirella and two Thalassiosira with remarks on morphology and evolution of East African Surirella and Thalassiosira.