In order to study the effect of co-substitution of Al(3+)and Cr3+ supercript stop for Fe-3+supercript stop in MgFe2O4 on its structural and magnetic properties, the spinel system MgAlxCrxFe2 - 2xO4 (x = 0.0-0.8) has been characterized by X-ray diffraction, high field magnetization, low field a.c. susceptibility and (57) Fe Mossbauer spectroscopy measurements. Contrary to the earlier reports, about 50% of Al3+ is found to occupy the tetrahedral sites. The system exhibits canted spin structure and a central paramagnetic doublet was found superimposed on the magnetic sextet in the Mossbauer spectra (0.5 > x > 0.2). Thermal variation of a.c. susceptibility exhibits normal ferrimagnetic behaviour.