The passive piezoelectric properties of composite structures containing PZT-5H rods embedded in epoxy resin and using transverse glass fibre reinforcement in a 3-1-1 connectivity have been investigated. In passive mode, it has been shown that dh and gh are strong functions of ceramic volume fraction, vf; respectively increasing and decreasing linearly over the range vf=0.063 to 0.277 for both 1 mm and 0.6 mm square ceramic rods. The dh.gh product is a much weaker function of vf. It has been demonstrated that the elastic modulus of the epoxy resin has a marked effect upon the dh.ghproduct obtained and results are presented showing the variation of gh with temperature and pressure up to 500 psi.