Theme T two-dimensional solid propellant sandwich has evolved as convenient test vehicle for theories dealing with both physical and chemical behavior of composite solid propellant ingredients. It allows detailed observation of the binder-oxidizer interface over range of test conditions. Sandwiches have been used by several investigators. Hightower and Price used laminated, two-dimensional sandwiches of single crystals of ammonium perchlorate and hydrocarbon binder. They considered this configuration to be a compromise between the complexity of the three-dimensional 'combustion zone' and the naivety of one-dimensional approximation. Jones investigated the catalytic behavior of Harshaw Catalyst, Cu 0202 and ferric oxide, Fe2O3 in solid propellant sandwiches of polycrystalline ammonium perchlorate (AP) and carboxyl terminated polybutadiene (CTPB). Hydroxyl terminated polybutadiene (HTPB) was substituted for CTPB and the behavior of the same catalysts over the pressure range 600-3200 psia was investigated. The sandwich vertical burn rate, the normal regression rate of the oxidizer and qualitative details of the deflagration process were obtained by cinephotomacrography. The current study has extended the investigation to include two additional catalysts,