Abstract Paroxetine is a widely consumed drug with antidepressant and anxiolytic activity prescribed in the treatment of related disorders, such as obsessive-compulsive disorder, panic fits, social phobias and post-traumatic stress. Molecular modelling analyses show that both semi-empirical methods (PM3 and AM1) give us approximated the same values of heat of formation, Total energy, binding energy, nuclear energy, Dipole moment, HOMO and LUMO energies, etc. And the Paroxetine molecule has a large negative heat of formation indicating that it is a molecule thermodynamically stable.