Performing calcinations of the support in different atmospheres is a vital precondition for preparation of active cobalt supported on MgO-La2O3 catalyst for ammonia decomposition. This work studied the influence of support calcination conditions on basic properties, morphology and catalytic performance. The catalytic performance was evaluated in the temperature range of 300-550 degrees C at atmospheric pressure. The XPS results showed the surface metal concentration was increased in 5 wt% Co supported on MgLa mixed oxide catalyst (5CMLa-N-2) whose support was calcined in N-2 atmosphere. The TPR measurements showed strong metal support interaction in 5CMLa-N-2 catalyst. From the SEM results the formation of MgLa mixed oxide was increased in 5CMLa-N-2 catalyst. The moderate basic site density determined by CO2 TPD results was increased in 5CMLa-N-2 catalysts compared with other catalysts. These outcomes are might be one of the reasons in enhancing activity in 5CMLa-N-2 catalysts compared to other catalysts. Hence support calcinations under N-2 being the best choice, was the one of the parameters that influenced on catalytic properties of the cobalt on MgO-La2O3 system, for ammonia decomposition. (C) 2016 Elsevier B.V. All rights reserved.