A 5 kW class shell and tube methane steam reformer (MSR) with intermediate temperature heat source was evaluated to find a correlation between the methane conversion and heat transfer performance. First, performance evaluation of MSR1 was conducted by varying experimental conditions such as reformer reactant flow rate, steam to carbon ratio (SCR), inlet temperature of reforming zone, and inlet temperature of heat source. Sensitivity study of overall heat transfer coefficient was also carried out to find the major parameter affecting the heat transfer. Next, the heat transfer performance and methane conversion rate of MSR1 and 2 were compared. Both reformers have the same gas hourly space velocity (GHSV) in the form of shell and tube heat exchangers, but are designed to compare the heat transfer characteristics of the reformer by designing with the different heat transfer areas. The results show that the main factors affecting the performance of the reformer are load, heat source inlet temperature, and heat transfer area. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.