RuS2 nanocrystallites were synthesized using a new technique, namely prolonged bubbling of H2S through a solution of RuCl3 in sulfolane and water at high temperatures. Optically transparent RuS2 colloidal particles could also be synthesized in hot sulfolane. Optical measurements of the RuS2 colloidal suspensions and powders showed a broad absorption in the visible spectral region, suggesting the suitability of this material for semiconductor sensitization experiments. The observed X-ray diffraction (XRD) data of the synthesized powder samples were in good agreement with the reported ASTM pattern of RuS2, confirming that RuS2 was the prepared compound by this new preparation technique. Scanning electron microscopic (SEM) pictures showed submicrometre sized crystallites. Heat treated powders of water prepared RuS2 showed < 50 nm particle sizes, and still smaller sizes were observed for the sulfolane prepared sample. Energy dispersive X-ray (EDX) analysis and X-ray fluorescence (XRF) measurements showed an Ru/S ratio of similar to 1:2 and also supported the XRD results.