Small naked ruthenium Sulfide nanoparticles (NPs) with narrow size distribution (2.5 +/- 0.4 nm of diameter) were synthesized in DMSO colloidal dispersions, under mild reaction conditions and using commercial RuCl3 as precursor. To test the chemical reactivity with soft and hard bases, fresh presynthesized RuS2 colloids were mixed with triethylamine (N(Et)(3)) and ammonium tetrathiomolybdate ((NH4)(2)MoS4) dimethyl sulfoxide solutions. Naked N(Et)(3) and [MOS4](2-)-capped RuS2 nanoparticle colloids were characterized using UV-visible electronic absorption and emission spectroscopies and high-resolution transmission electron microscopy (HR-TEM). It has also been shown that capped RuS2-[MoS4](2-) nanoparticles yield MoO3 crystalline matrix by means of HR-TEM experiments. The emission spectra of RuS2 and N(Et)(3)-RuS2 dispersions show that both nanosized materials have strong fluorescence. The existence of the ruthenium precursor species ill solution was established by cyclic voltammetry. Moreover, naked RuS2 NPs were mixed with a chemical mixture with composition similar to gasoline (dibenzothiophene (Bz(2)S, 400 ppm), hexane, and toluene (55:45% v/v)). The reaction Mixture consisted of two phases; in the polar phase, we found evidences of a strong interaction of Bz(2)S and toluene with the naked RuS2 NPs. We have also obtained self-organized thin films of capped N(Et)(3)- and RuS2-[MOS4](2-) nanoparticles. In both cases, the shape and thickness of the resulting thin films were controlled by a dynamic vacuum procedure. The thin films have been characterized by atomic force microscopy, scanning electron microscopy, HR-TEM, energy dispersion spectroscoy, X-ray diffraction, and absorbance and fluorescence spectroscopies.