This article presents the accomplishments and challenges of a rural sustainable development initiative in Nyanza Province, Kenya. Our focus is on the sale and financing of a simple technology — an improved cookstove — by a local entrepreneur. The theoretical basis of the research is innovation systems and (social) entrepreneurship. We first define the major challenges of the diffusion process encountered throughout the initiative’s early years, with special concentration on maintaining the working capital to sell and finance additional innovations. We next present the measures to address the challenge, including detailed written contracts, a modest fee for late payments, a contract-signing witness, and money-transfer options by mobile telephone. We subsequently present repayment rates for up to one year after implementing the changes, which show a general pattern of improvement. Finally, we discuss the sustainability of the technology, repayment rates, innovation systems, and entrepreneurship in sub-Saharan Africa. The main message of the research is that the major challenge is not creating more sustainable technologies, but overcoming difficulties in diffusion processes.