I will present VULCAN, a 1D chemical kinetics code suited for the temperature and pressure range relevant to the observable exoplanetary atmospheres. The chemical network is based on a set of reduced rate coefficients including C/H/O mechanism. Most of the rate coefficients can be found on the NIST online database. The kinetics network is compared with the thermodynamic equilibrium code, and the difference between the experimentally measured rates and the thermodynamic reverse rates is examined. Some test runs of VULCAN are shown in a hierarchical way: pure H, H+O, H+O+C. Controlled experiments are performed with a simple analytical temperature-pressure profiles. Different parameters, such as the stellar irradiation, atmospheric opacities and albedo are explored, in order to understand how these properties affect the temperature structure and hence the chemical abundances. I will also discuss the "transport-induced-quench" due to vertical mixing and the limitation of this approximation.