Complex reactions proceed via a large number of elementary reaction steps involving reactants, reaction intermediates and products. The kinetic characteristics of the reaction steps are normally subject to rigorous thermodynamic constraints such as Wegschieder conditions. The enumeration and implementation of these constraints in complex reaction mechanisms may be tedious. In this presentation we show that the problem of thermodynamic consistency of reaction mechanisms may be naturally treated in terms of reaction route networks. Moreover, a reaction route networks cannot be assembled in principle if all of the thermodynamic constraints placed on a reaction mechanism are not satisfied. The approach is illustrated with examples of various microkinetic models.