Electronic Journal of Differential Equations, Vol. 2012 (2012), No. 87, pp. 1-20. Title: Generalized Heaviside functions in the Colombeau theory context Author: Francisco Villarreal (FEIS-UNESP, Sao Paulo, Brazil) Abstract: We defined generalized Heaviside functions for a variable x in $\mathbb{R}^n$, and for variables (x,t) in $\mathbb{R}^n\times\mathbb{R}^m$. Then study properties such as: composition, invertibility, and association relation (the weak equality). This work is developed in the Colombeau generalized functions context. Submitted November 1, 2011. Published June 04, 2012. Math Subject Classifications: 46F30, 35G20. Key Words: Generalized function; Heaviside function; distribution.