This paper describes, compares and analyses the historical development and current status of Kenya's and Tanzania's emerging solar energy markets. The analysis is based on an extensive literature survey and 25 in-depth personal interviews with experts on the East African solar power market. Kenya's solar market is found to be one of the world's leading markets for off-grid solar uses, with a current installed capacity of over 10 MWp and more than 320,000 solar home systems. Having developed much later than the Kenyan market, Tanzania's market still remains smaller than its neighbour's, with an installed capacity of around 4 MWp and at least 40,000 solar home systems, but is in the process of catching up. In addition to solar home systems, other applications of solar energy technologies, such as in social institutions, telecoms and tourism, are covered. Major differences and similarities between the Kenyan and Tanzanian solar markets are identified and reasons for these are analysed. Initial policy implications regarding the regulation and promotion of solar energy in East Africa suggest that awareness, availability and affordability are major drivers that all need to be present to enable the widespread adoption of off-grid solar technologies in emerging markets. (C) 2013 Elsevier Ltd. All rights reserved.