In the present paper, a temperature-dependent equation of state (EOS) of condensed matter is discussed, which is capable of predicting the high-pressure and high-temperature behaviour of solids and liquids. The EOS can be used to obtain the volume compression, the isothermal bulk modulus and its first pressure derivative, the thermal expansion coefficient and the Anderson - Grüneisen parameter, together with other thermodynamic properties as functions of pressure at different temperatures. The present EOS has been applied for Au, Mo and W and liquid Hg. Good agreement between theory and experiment is observed.