Aqueous ruthenium (III) chloride (RuCl3.3H2O) solution (0.03M) was sprayed on pre-heated ordinary glass substrates. Amorphous ruthenium oxide thin films were obtained, which were sulfurized under vacuum at several lower heat treatment temperatures (400, 450, 500 and 550 ℃) in RTP oven. The XRD results indicated the appearance of the RuS2 phase for all the sulfurization temperatures. The layer compositions were confirmed by EDS analysis. Monocrystalline and polycrystalline RuS2 thin films were obtained. SEM images showed mix of morphologies (filament, particles, and clusters) with porous surfaces. High absorption coefficients were deduced. The obtained RuS2-thin films showed different direct band gaps (1.43, 1.80, 1.79, 1.83 eV), which make it a distinct energy conversion and storage material. The opto-electrical properties of the as obtained RuS2-thin films make them among the best candidats for several applications, such as low cost material for low cost solar cells, and for alkaline hydrogen evolution electrocatalysts.