Several non-vacuum based approaches have been employed to deposit the Cu(In,Ga)Se2 layer in photovoltaic devices, but most of them use processing temperatures in the vicinity of 500°C. Here, we present the results on a facile solution-based deposition technique for CuInSe2 (CISe) and CuIn(S,Se)2 (CISSe) thin films with deposition temperatures of 300°C. CuxSe (1.5≤x≤2) or CuyS (1≤y≤2) precursor films deposited on a substrate were reacted with InCl3 and Se reactants in oleylamine to form CISe or CISSe thin films of the desired thickness, composition and crystal structure. Solar cells processed from these films on Mo-coated glass substrates demonstrated an efficiency of 2% under AM 1.5 illumination. We also present external quantum efficiency and capacitance–voltage measurements from these devices providing insights into the device performance. ► We present a solution-based deposition technique for CuInSe2 films at 300°C. ► Lower temperatures, same number of steps enable processing on flexible substrates. ► Solar cells demonstrate an efficiency of 2%.