A series of terms of the perovskite system LaCr1-xMgxO3 (x = 0 divided by 0.5) were synthesised by the so-called ’citrates method’, characterised and tested for application in the catalytic combustion of methane. Catalysts have been prepared either in an unsupported or in a MgO-supported form, obtaining, in this last case, higher catalytic activities owing to a better dispersion of the catalytically active species. Mg-doping of the basic LaCrO3 perovskite promotes catalytic activity in proportion to Mg/Cr substitution. An Eley-Rideal mechanism (oxygen dissociative chemisorption on catalytically active sites and reaction with methane) could satisfactorily fit the experimental results of a kinetics analysis performed on some supported perovskite catalysts with comparatively high x values (0.2-0.4).