Thin CuInSe2 films were prepared by one-step electrodeposition process. The deposition was done in potentiostatic regime from an original electrolyte containing Cu+, In3+, Se4+ ions and thiocyanate as a complexing agent. The influence of deposition parameters (electrolyte composition and concentration, temperature of the electrolyte and deposition potential) on film composition was studied. Technological parameters for preparation of films with a desired composition were found. The as-deposited films were heat treated in Ar and in Se ambient. Morphology and structure of as-deposited and of annealed films were investigated. It was established that Se treatment was more effective than the annealing in Ar in addition to crystallite size. Phase formation after Se treatment was elucidated. It was found that composition of as-deposited films mainly conditioned phase composition after the selenization.