The superconducting properties of the Ti-Y-Ba-CwO high-T, superconductor are measured in applied magnetic fields up to 20 T. The mechanical and magnetic properties and dB!,/dT and dBb2/dT are determined for a wide range of TiO, doping concentrations. Significant improvements of the mechanical properties and of dBi,/dT are observed. The optimum concentration for doping with TiO, is determined.