In the BGL slagging gasifier, graded coal is gasified in a fixed reactor. A study has been made of the carbonization of large particles (similar to 25-30 mm) of three high-volatile UK bituminous coals at pressures in the range 0.5-8 MPa in an autoclave using a shock beating technique. The cokes were characterized in detail and compared with the corresponding high-pressure cokes produced under slow heating conditions. The coke yields increased significantly with increase in carbonization pressure. On the other hand, cokes produced under shock heating conditions resulted in a lower yield than the corresponding cokes prepared under slow heating conditions. These shock-heated cokes gave higher relative apparent densities and exhibited greater strength, such as higher abrasion resistance.