A steady-state model of a coal-fired circulating fluidized-bed (CFB) boiler considering the hydrodynamics, heat transfer, and combustion is presented. This model predicts the flue gas temperature, the chemical gas species (O-2, H2O, CO, CO2, and SO2), and char concentration distributions in both, the axial and radial location along the furnace including the bottom and upper portion. The model of the gas-solid flow in the dilute regime calculates solid volume concentrations and local solid velocity. The model was validated against experimental data generated in a 35 t/h commercial CFB boiler with a low circulation ratio.