Kisumu is a port city in Kisumu County, Kenya , with a population of 409,928 (2009 census). It is the third largest city in Kenya, the principal city of western Kenya, the immediate former capital of Nyanza Province and the headquarters of Kisumu County. It has a municipal charter but no city charter. It is the largest city in Nyanza region and second most important city after Kampala in the greater Lake Victoria basin.