The performance of the cross‐flow turbine, CFT, also known as the Banki turbine, was studied experimentally by varying the number of blades, the runner diameter, and the nozzle entry arc under flow/head variations. The results, as presented in this paper, show that the maximum efficiency of the CFT at any flow/head combination increases as the nozzle entry arc increases or the aspect ratio of the runner decreases. Equations have been suggested to obtain the optimum number of blades for maximum efficiency of the turbine and to find the specific speed of the CFT as a function of unit discharge and nozzle entry arc.