The asymmetric unit of the title compound, (C(13)H(15)N(2)S(2))[RuCl(3)(C(10)H(14))], contains a 1,3-(2-thienylmeth-yl)-4,5-dihydro-imidazolium cation and a trichlorido(η(6)-p-cymene)ruthenate(II) anion. The thio-phene rings of the cation are disordered by an 180° rotation about the thio-phene-CH(2) bonds with occupancies of 0.847 (5)/0.153 (5) and 0.700 (5)/0.300 (5), respectively. The Ru atom exhibits a distorted octa-hedral coordination with the benzene ring of the p-cymene ligand formally occupying three sites and three Cl atoms occupying the other three sites. The short C-N bond lengths in the imidazoline ring indicate partial electron delocalization within the N-C-N fragment. Cation and anions are connected through five inter-molecular C-H⋯Cl hydrogen bonds and one C-H⋯π hydrogen bond, forming a three-dimensional hydrogen-bonded network.