The present invention provides a new process of the transitiometric scanning technique to determine in an experimental way the minimum miscibility pressure of any sample of hydrocarbon at constant temperature (from the atmospheric temperature to 673 K) in the pressure interval of the atmospheric temperature to 400 MPa, including pressure at which the organic matter will precipitate due to the CO2 injection, based on a transitometric technique which has proved to be reliable, highly accurate and highly reproducible. The apparatus used is based on a highly accurate control of the pVT variables and the calorimetric determination of the present phase transitions during the injection process of gases into hydrocarbons. Accurate control of pVT variables enables the determination of the derivative thermodynamic variables useful to define the type of phase transition.