Spark plasma sintering (SPS) is one of the advanced consolidation techniques developed in the last few decades. We have studied the decomposition behavior of MgH2 and MgH2/graphite 1:1 mixtures in the SPS process. The standard SPS setup chosen was modified by including the temperature measurement inside the sample, so that the data can be compared with findings from thermal analysis. The results show clearly the reduction of the decomposition temperature measured in the SPS process if the necessary conditions (sufficient current density by applying the insulation) are realized.