This work comprises the systematic study of a monolithic reactor design for steam methane reforming (SMR) to achieve optimal dimensions for the highest rate of reaction. The design is developed using an analytical model to establish the optimum length of the reactor. The result is confirmed by a computational fluid dynamics (CFD) model. Experimental work on SMR is carried out in lab scale. In the analytical models, the design equations for the square channel reactor are derived to estimate the channel length that affords the highest rate of reaction. The optimum length is determined as 41.6 mm with a reaction rate of 2.88 x 10(-8) mol/s at the channel height of 1.5 mm, 873 K, and 1 atm. The respective optimum channel length from the CFD and experimental results are 80.0 mm and 90.0 mm, respectively, with respective reaction rates of 7.42 x 10(-7) mol/s and 6.85 x 10(-7) mol/s. The effects of channel heights ranging from 0.5 to 3.0 mm are investigated by CFD. Methane conversion per unit channel perimeter is defined as a design parameter for the sizing and rating of this platform. The highest value (50% mm(-1)) is afforded at a channel height of 0.50 mm. (C) 2018 Elsevier Ltd. All rights reserved.