In this work, the effect of different annealing treatments on the phase transition, structural behaviour and thermal analysis of MnCoGe alloys has been analysed. The changes in the transition temperatures have been studied by Simultaneous Thermal Analysis (STA). The results show that the structural transition temperature (Tstr) depends on the annealing treatment of the samples preparation. However, under the same heat treatment no significant change is observed on the curie temperature (Tc). The thermal analysis reveals endothermic peak which corresponds to the structural phase transition of the compounds. The microstructural evolution has been monitored using in-situ X-ray diffraction which made known this compound produce three type of structures which are hexagonal, orthorhombic and mix structure (hexagonal and orthorhombic).