Abstract: The active radicals produced in the photolysis of substituted titanocene dichloride complexes (RC₅H₄)₂TiCl₂ (R=CH₃ C₂H₅, C₃H₇, C₅H₁₁, C₆H₁₁) have been studied by combination of spin trapping technique with ESR spectroscopy Results show that the primary process of photolysis is homolytic cleavage of the Ti-RC₅H₄ π bond, with the formation of (RC₅H₄)^· radical and (RC₅H₄) TiCl₂ fragment. The (RC₅H₄)^· radical can be trapped by nitrosodurene (ND) to form two spin adducts and their concentration ratio is about 1:1.