The material Gd5(Si[Subscript x]Ge[Subscript 1-x])4, with x [Equals approximately symbol] 2 was investigated using electron microscopy. The material possesses a complex crystallographic structure and undergoes a unique, reversible, transformation at low temperatures and an irreversible high temperature transformation. Alloys produced by induction melting and arc melting were examined and the phases identified. The results of SEM and TEM studies of the high, room and low temperature microstructures are reported. Direct observation of the transformation with a discussion on the mechanism of the reversible, low temperature, phase transformation is detailed.