Hydropower, large and small, remains by far the most important of the “renewable” for electrical power production worldwide. Small-scale hydro is in most cases “run-of-river”, with no dam, and is one of the most cost-effective and environmentally benign energy technologies to be considered both for rural electrification in less developed countries and developed countries for further hydro developments countries(like Ethiopia). This paper addresses power generation for rural applications by means of small hydropower plants by using cross-flow turbine systems .The cross-flow turbine is suitable for installing small hydro-electric power plants in case of low head and flow rate. Using mathematical analysis a complete design of such turbines has been done in this paper.