A new solution to Dielectric Characterization problem of Inhomogeneous Media is developed using a meta heuristics based optimization tool. A Particle Swarm Optimizer is resorted to estimate the dielectric permittivity of a multi layered building media by using free space transmission measurement technique and where EM fields propagation is modeled using the TLM method. The performances of the proposed characterization system which are illustrated through some selected examples form building materials show the validity and accuracy of the proposed approach.