The Mn-Ge binary system is a potential candidate to the fabrication of Spintronic devices. However, the understanding of the contribution of each possible Mn-Ge phase is crucial. In this work, the reaction between 50 nm thick Mn film and amorphous Ge substrate was studied via in-situ XRD. These experiments lead to the identification of the Mn-germanides formed during the reaction, with structural and magnetic confirmation. Besides, a sequence of germanides formation is studied and proposed.