An arene ruthenium(ii) complex coordinated with 2-(2-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, [(η6-C6H6)Ru(o-ClPIP)Cl]Cl (1), has been prepared by using microwave-assisted synthesis technology. The anti-tumour activity of this complex against various tumour cells has been evaluated by MTT assay and the results show that complex 1 exhibits selective inhibitory activity against the growth of human lung adenocarcinoma A549 cells with IC50 = 31.58 μM. Further studies by flow cytometric analysis showed that apoptosis of A549 cells was observed when dealt with complex 1. Furthermore, complex 1 exhibits excellent binding affinity with DNA molecules which was confirmed by spectroscopy methods, as well viscosity and melting point experiments. As a result, the conformation of DNA molecules was disturbed by complex 1.