This work presents a) an analytic model based on homogenizationestimates to obtain explicit solutions for the effective properties ofparticulate piezoelectric composites and b) a three-dimensionalfinite-element model to compare finite-element results and study thebehaviour of porous piezoelectric composites with four differentgeometric configurations. The analytic model extends the Suquet estimates method to the piezoelectric domain where acomplete set of electromechanical constants are obtained for threepiezoelectric ceramics belonging to different symmetry classes.Specific results are generated for the cases of a square arrangementof cylindrical pores, where the alignment of the pores is in thedirection of poling of the matrix phase and a cubic arrangement ofspherical pores. The trends obtained from the analytic model arecompared with the finite-element model and found to be in goodagreement for all components of effective piezoelectric constants uptolarge volume fractions. A three-dimensional finite element model isdeveloped in part II of the thesis to completelycharacterize the behaviour of a general porous piezoelectric compositewith pores of 0-3 type flat cuboidal, 0-3 type cylindrical, 0-3 typespherical, and 1-3 type cylindrical connectivities. By consideringmaterials from different symmetry classes, it is demonstrated thatpiezoelectric composites designed with 0-3 type flat cuboidal poresare more suitable for hydrophone applications by identifying thevariation in piezoelectric strain coefficient and the hydrostaticfigure of merit with varying porosity volume fraction.