Plasma catalysis, combining the advantages of fast ignition/response from plasma and high selectivity from catalysis, is a novel technique for hydrocarbon reforming to produce H2. It has been experimentally demonstrated that such a combination could result in a synergistic effect, i.e. the performance achieved with plasma catalysis is better than the summation of plasma-alone and catalysis-alone. According to the location of catalyst, this novel technique can be divided into two categories, namely, single-stage and two-stage systems. In this study, a comprehensive review on the interactions between plasma and catalysis possibly leading to the synergism in different plasma catalysis configurations has been given to provide useful information for further optimization. Moreover, a brief introduction regarding an onboard plasma catalysis reformer for motorcycle engines developed by the authors is also provided. The experimental results indicate that the fuel consumption and pollutant emission could be effectively reduced with the assistance of the reformer.