This chapter describes various methods for storing chemical kinetic mechanistic information within combustion models. The most obvious way is the definition of the kinetic system of differential equations by a detailed reaction mechanism. Parameterisation of such reaction mechanisms is commented upon here. Another possible approach is to store the solution of the system of ordinary or partial differential equations that defines the model within look-up tables. Such data can then be “retrieved” during combustion simulations within complex reacting flow models instead of solving the kinetic system of differential equations, often at much lower computational cost. Several such methods for storage and retrieval are reviewed here. As an alternative approach, functional representations of the time dependant kinetic changes or the look-up table contents can be achieved, using for example polynomial functions or artificial neural networks and these are also discussed.