Systematically exploring candidate reaction pathways of chemical and biochemical reactions has both theoretical and practical importance. For example, on the basis of the understanding of the mechanism of a complex reaction, its yield may be improved. For this reason many works cover issues on the synthesis of reaction pathways for a given reaction. One of the most effective approach is based on P-graph algorithm capable of generating all possible reaction pathways from the starting reactants (precursors) to final products (targets). This method produces the possible topological structures of the reaction based on dynamic equilibrium state, steady-state circumstances. It is, therefore, crucial to know whether these states can be reached from the initial state of the system, i.e., whether the reaction pathway is structurally startable. A novel algorithm is given in the present work that examines the reaction pathways in terms of structural startability. The algorithm has been demonstrated by applying hydrogenation of ethylene to ethane on biactive-site platinum catalysts. The reduction of the number of potential pathways to be examined during the selection of the best reaction mechanism contributes to the efficiency of reaction engineering.