A three-dimensional (3D) computational fluid dynamics (CFD) model of an annulus steam methane reforming (SMR) reactor was developed for producing 2.5 Nm(3)/h of H-2 from natural gas. The feed and combustion gases played a role in a counter-current heat exchange owing to a narrow sleeve equipped between the combustor and catalytic reactor. The momentum, energy, and mass conservation equations were integrated with a realizable k-epsilon turbulence model, discrete ordinates radiation model, and reversible SMR reaction kinetics. The CFD results such as axial temperature profiles and producer gas compositions were validated against the experimental data measured in this study. The thermal efficiency of the compact SMR reactor was 60%, and the heat flux through the reactor wall was 39 kW/m(2). The overall heat transfer coefficient from the sleeve to the catalytic reactor was 158 W/m(2)/K. The sleeve-type SMR reactor flattened the temperature profile along the reactor length.