An alternative way for synthesis of methanol at temperatures lower than the current industrial practice is an indirect, two-step synthesis via methyl formate. An integrated two-stage reactor (ITSR) was designed and tested for the two-step synthesis to overcome problems encountered in single-slurry-reactor operation. The results show that the ITSR can be operated successfully at a broad range of conditions. For syngas conversions similar to that of the current industrial practice, the ITSR can be operated at much milder conditions. Under the conditions used in the study, the mass transfer of CO from the gas phase to the liquid phase is the rate limiting step in the transient period, and the evaporation of the intermediate, methyl formate, from the liquid phase to the gas phase is the rate limiting step at steady state. Temperature, pressure and feed flow rate showed significant influence on the synthesis reaction.