A comprehensive dynamic mathematical model was developed to analyze methanol-steam reforming in catalytic packed-bed reactor. The contributions of all molecular and convective terms of momentum, heat, and mass transfer were taken into consideration, with the inclusion of effectiveness factor. Effects of two predominant parameters: particle size and the wall heat flux on the reactor performance for the methanol-steam reforming were examined. It was revealed that by increasing the average particle size from 700 to 3200 mm, which corresponded to porosity values of 0.4 and 0.6, the effectiveness factor decreased by nearly 80% and subsequently the overall methanol conversion decreased by around 74%. Besides, through a set of organized simulation runs, it was discovered that with increasing the dimensionless wall heat flux from 0 to 0.2 Wm(-1) K-1, the methanol conversion was enhanced by 87%.