We report on the synthesis and characterization of second generation ruthenium indenylidene catalysts bearing unsymmetrical N-heterocyclic carbene (NHC) ligands denoted as RuCl2(3-phenyl-1-indenylidene)(1-mesityl-3-R-4,5-dihydroimidazol-2-ylidene)(PCy3), in which R is methyl , octyl or cyclohexyl . The characterization of was performed by NMR spectroscopy, elemental analysis, IR, HRMS and single-crystal X-ray diffraction analysis. In addition, the catalytic activity of the obtained initiators was evaluated in various representative metathesis reactions. The results reveal that the complexes , bearing an N-alkyl side on the NHC, show a faster catalytic initiation than the reference complex . Complex , which performs the best among the investigated indenylidene complexes, exhibits slower initiation but better overall efficiency than its benzylidene analogue , especially in a low catalyst loading.