The oxygenation of MT-YBCO under isostatic oxygen pressure (up to 16 MPa) at 900-800 deg C allowed reduced process time, lower macrocracking, and reduced microcracks. Additionally higher critical currents, trapped fields and mechanical characteristics can be attained. At 77 K thin-walled MT-YBCO had a jc in the ab plane of 85 kA/cm2 at 0 T and higher than 10 kA/cm2 in fields up to 5 T and the irreversibility field was 9.8 T. In the c-direction jc was 34 kA/cm2 in 0 T and higher than 2.5 kA/cm2 in a 10 T field. At 4.9 N-load the micohardness, Hv, was 8.7+/-0.3 GPa in the ab-plane and 7.6+/-0.3 GPa in the c-direction. The fracture toughness, K1C, was 2.5+/-0.1 MPa*m0.5 (ab-plane) and 2.8+/-0.24 MPa*m0.5 (c-direction). The samples with a higher twin density demonstrated a higher jc, especially in applied magnetic field. The twin density correlates with the sizes and distribution of Y211 grains in Y123. The thin-walled ceramics that demonstrated the highest jc contained about 22 twins in 1 mum and were practically free from dislocations and stacking faults. The maximal trapped field of the block of thin-walled ceramic oxygenated at 900-800 deg C and 16 MPa was doubled as compared to that oxygenated at low temperature under ambient pressure.