The purpose of this work is to study the performance of fixed and monolith bed reactors in Fischer-Tropsch (FT) synthesis by modeling these reactors. A pseudo-homogeneous 2D model was proposed for FT fixed and monolith bed reactors. The model results shows good agreement with experimental data reported in literatures. The performance of the FT reactors was investigated in industrial scale under low temperature FT conditions (pressure = 2 MPa and temperature = 230 °C). The modeling results were organized in three sections, (1) effect of operating condition parameters, which have similar effects on both reactors, (2) effect of structure parameters, which have different effects such as pellet diameter on FT fixed bed reactors, and thermal support property, the number of channels per cross sectioon area (CPSI) and wash coated catalyst thickness on FT monolith bed reactors, and (3) comparison of FT fixed and monolith bed reactors.