We report structural and electronic properties of the compounds known as Nowotny chimney–ladder (CL) phases RuAl2, RuGa2 and OsAl2 using the full potential linearized augmented plane wave (FP-LAPW) method. For treating the exchange–correlation potential term, we have chosen the generalized gradient approximation (GGA) and the total energy approach is used to determine the equilibrium volume. The energy gap is found to be indirect for all our compounds. In addition to that, a detailed description of the electronic properties such as band structures, density of states and electronic charge densities has been also performed. To our knowledge, there are no correlative experimental and calculated results about the dielectric function for this material and we consider the present results as a prediction study for those compounds.