This report describes the MPI parallelization of the combustion code Ares. First, the structure of the code is described, then a detailed analysis of the algorithms used to integrated the flow equation is carried out, with particular emphasis to the parallelization issues. An analysis of few possible alternative approaches is then followed by the description of the chosen approach. A preliminary validation of the parallel code completes the report. Thorough validation on 3D complex test cases will be presented in the next report.