Ni-based (over MgO and Al2O3) and noble metal-based (Pd and Pt over Al2O3) catalysts were prepared by wet impregnation method and thereafter impregnated in microreactors. The catalytic activity was measured at several temperatures, atmospheric pressure and different steam to carbon, S/C, ratios. These conditions were the same for conventional, fixed bed reactor system, and microreactors. Weight hourly space velocity, WHSV, was maintained equal in order to compare the activity results from both reaction systems. For microreactor systems, similar activities of Ni-based catalyst were measured in the steam methane reforming (SMR) activity tests, but not in the case of natural gas steam reforming tests. When noble metal-based catalysts were used in the conventional reaction system no significant activity was measured but all catalysts showed some activity when they were tested in the microreactor systems. The analysis by SEM and TEM revealed a carbon-free surface for Ni-based catalyst as well as carbon filaments growth in case of noble metal-based catalysts. ► Hydrogen production from methane and natural gas steam reforming process was studied. ► Two different reaction systems were used: fixed bed reactor and microreactor systems. ► Ni/MgO catalyst was more selective for WGS reaction than Ni/Al2O3 catalyst. ► Ni/Al2O3 catalyst suffered a quick deactivation in natural gas SR process. ► For Pd/Al2O3 and Pt/Al2O3catalysts a very low activity was measured.