Mathematical formulations of heat conduction in thin films and subsequent analytical solutions are the subject of this paper. A generalized formulation of the energy equation that allows for local nonequilibrium conditions between the heat carriers is valid for a broad spectrum of materials from conductors to nonconductors. A unified solution is derived from the classical solution of the energy equation and it is cast as a modification of the Green＇s function solution for Fourier heat conduction. Numerical examples show the influence of periodic surface heat flux on phase angle and temperature. and the condition for lumped system approximation.