A novel Ru(II) complex of [Ru(bpy) 2 (Hbcpip)](ClO 4 ) 2 {where bpy=2,2-bipyridine, Hbcpip=2-(4-(9H-3,9′-bicarbazol-9-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} is synthesized and characterized. Calf-thymus DNA-binding properties of the complex were studied by UV–vis absorption and luminescence titrations, steady-state emission quenching by [Fe(CN) 6 ] 4− , DNA competitive binding with ethidium bromide, thermal denaturation and DNA viscosity measurements. The results indicate that the complex partially intercalated into the DNA with a binding constant of (5.5±1.4)×10 5 M −1 in buffered 50mM NaCl. The acid–base properties of the complex were also studied by UV–visible and luminescence spectrophotometric pH titrations, and ground- and excited-state acidity ionization constant values were derived.