Many types of atmospherical compounds and radicals have a high enthalpy. Otherwise, they can react between them or with the O 3 of the ozone layer. Therefore, these reactions generate consequences, such as ozone layer depletion, acid rise of the atmosphere, acid rain, greenhouse effect, etc. In this studio, we present the computational calculation of the enthalpy of formation of some organic compounds which have been emitting since the Industrial Revolution by the human activity.