Perovskites as host structures of cations were used in order to generate in situ active and stable catalysts for ethanol steam reforming. For this purpose, La1-xMgxAl1-yNiyO3(x=0. 1; y=0, 0. 1, 0. 2, 0. 3) perovskites were synthetized by the citrate method. Ni segregation is evident for a substitution level higher than 0. 2. The segregation of Ni as NiO generated species interacts with different metal-support after the reduction step. The y=0. 1 catalyst presents the highest H2yield value about 85% during reaction time, with low mean values of CH4and CO selectivities of 3. 4% and 11% , respectively and a low carbon formation. The better performance of y=0. 1 catalyst could be attributed to the minor proportion of segregated phases, thus a controlled expulsion of Ni is successfully reached.