The effects of alloy composition on the formation temperature and electrical resistivities of C54 titanium germanosilicide formed during the Ti/Si1-xGex (x=0, 0.3, 0.4, 0.7, 1) solid state reaction have been investigated. Ti5(Si1-yGey)3, C49– and C54–Ti(Si1-zGez)2 were observed to form in the Ti/Si1-xGex (x≥0.4) systems. On the other hand, Ti6(Si1-yGey)5 and C54–Ti(Si1-zGez)2 were found in the Ti/Si1-xGex (x≧0.7) systems. For both cases, the relationship of x≫y≫z was found. The appearance and agglomeration temperature of low-resistivity C54–Ti(Si1-zGez)2 were both found to decrease with the Ge concentration. The resistivities of C54–Ti(Si1-zGez)2 were measured to be 15–20 μΩ/cm. The segregation of Si1-wGew (w≫x) was found in all samples annealed above 800 °C. The effects of thermodynamic driving force, kinetic factor, and composition of the micro-area are dis- cussed. © 1999 American Institute of Physics.