Surface chemistry of as-prepared 3CSiC nanoparticles obtained by electrochemical etching of bulk 3CSiC substrates was studied. Chemical environment was found to influence strongly the photoinduced electronic transitions in the 3CSiC nanoparticles. The influence of different interfacial chemical environments of the 3CSiC nanoparticles, such as surface chemistry, solvent nature, and surface charges on the photoinduced absorption and luminescence of the nanoparticles at room temperature, is described and discussed in detail. For example, oxidation induced passivation of the radiative band gap states allows visualization of the transitions between energy levels in the nanoparticles in which photogenerated charge carriers are quantumly confined. Electrostatic screening of the radiative band gap states by highly polar solvent media leads to a blueshift and a decrease in the width at half maximum of the photoluminescence spectra of the nanoparticles. As for the surface charges, they govern band bending slope and thus influence strongly the radiative transitions via energy states in the band gap.