Abstract This study reports the synthesis, structure and magnetic properties of Sr 2−xLa xCrMoO 6 and Sr 2−xLa xCr 1+x/2Mo 1−x/2O 6 samples. Although both series exhibit similar crystal structures, Sr 2−xLa xCrMoO 6 samples present an effective electron doping revealed by a significant expansion of the unit cell with increasing x. In Sr 2−xLa xCr 1+x/2Mo 1−x/2O 6 samples instead, the Cr-excess leads to a non electron doped system. Both series show a large amount of antisite defects whose number increases as La-content increases. Neutron diffraction patterns reveal the existence of long-range magnetic ordering for all samples but the magnetic peaks are very broad for Sr 2CrMoO 6 indicating a short coherence length of the magnetic ordering. This coherence length is increased upon replacing Sr by La. In both systems there is a clear increase of the magnetic transition temperature with increasing the La-content. The samples show ferromagnetic contributions at low temperature as deduced from the magnetic hysteresis loops typical of hard ferromagnetic materials. However, magnetic saturation is not achieved even at 5 T and the magnetic moment at this field is small. The ac magnetic susceptibility reveals the existence of several anomalies suggesting that these compounds are magnetically inhomogeneous. This is probably due to the presence of the large amount of structural defects not homogenously distributed.