A detailed investigation of the pressure and temperature dependence of the structure of stable and metastable solid Ge phases in the 0-15 GPa and 295-500 K ranges is presented. Structural results including the equation of state, characteristic of coexistence regions of diamond and P-tin structures, and appearance of metastable phases are discussed and compared with the results presently available in the literature. The isothermal bulk modulus and its derivative are evaluated using temperature-dependent equations of state for Ge I (cubic) and Ge 11 (beta-Sn), and for the Ge III (ST12) metastable polymorph at 400 K