The purpose of this study is to model mathematically the equation of the lightning return current in tropical zones and to validate it with data obtained from direct measurements in Colombia and Brazil. This study is carried out because the lightning return current in tropical zones is greater than in other latitudes of the planet. For this reason, it is very important for different applications in electrical engineering. Nowadays, the Heidler equation is used for the simulation of faults in electrical systems. This equation will serve as a reference to make a comparison between the data of the equation obtained in this article with those from the equation of Heidler.