The hydrogenation of m-dinitrobenzene to m-phenylenediamine in liquid phase was studied with the platinum catalysts supported on TiO2, Al2O3 and TiO2-Al2O3 carriers. These materials were successfully activated either by simple in situ reduction technique that makes use of the same reaction conditions or conventional reduction with H-2 flowing at 723K. Among the catalysts tested, the Pt/TiO2-Al2O3 catalyst showed the highest activity and selectivity towards m-phenylenediamine, over which 99% m-dinitrobenzene conversion and 97% m-phenylenediamine selectivity were obtained at 363K under hydrogen pressure of 8,1 MPa after reaction for 22 h when using ethanol as solvent and the catalyst was previously activated by the in situ activation method.