This paper analyses some recently published data on chemical reactions in supercritical fluids where the reaction mixture, i.e. reactants or a component of a complex reaction mixture is in the supercritical condition. Besides the theory which explains the influence of pressure on the reaction rate constant in supercritical conditions, other processes (extraction, reaction with homogeneous or heterogeneous catalyst) were also analyzed. Furthermore, catalytic processes in which a change of phase conditions ocurs, processes of catalyst regeneration, processes of oxidation by water which is in the supercritical conditions (SCWO), ionic reactions in the supercritical condition, enantioselective or biocatalyzed reactions, as well as polymerization are also presented.