This review article deals with the recent work published on the catalytic activity of transition metal oxides of group IV of the periodic table. These oxides are mainly in the form Of MO2, where M refers to either titanium, zirconium, or hafnium. The preparation of the pure, mixed, and supported oxides, as well as the characterization of their physicochemical properties, are briefly reviewed. However, their catalytic performance in various chemical reactions have been presented in detail. The photocatalytic activity of TiO2 in many photochemical degradation and conversion processes has been also discussed. Strong emphasis is put on discussion such as the nature and strength of active sites, adsorption of target compounds, kinetic parameters, and reaction mechanisms.