Injection molded piezocomposite materials have significant potential for improving the performance of Navy and civilian acoustic systems. Specifically, a 1-3 configuration based on PZT exhibits attractive properties for hydrophone array systems where the elements are many and/or small. An array of 1-3 composite hydrophones has been manufactured and tested as a potential replacement for a currently used 0-3 composite (Piezo-rubber) hydrophone array developed for a high frequency sonar. For this application, several experimental composite panels have been manufactured from injection molded PZT-5H and PZT-4 ceramic, each of which contains 20 or 40 elements. Acoustic modeling and test results have been obtained for two configurations of interest: the array panel alone; and the panel installed in a housing similar to the finished hydrophone module. Results will be presented which include: predictions of sensitivity and phase response; predictions of self-noise candidate material, including future designs with smaller elements; acoustic measurements (sensitivity, beam patterns, relative phase) for the test panels alone; acoustic measurements for the panels mounted in the housing. A companion paper (R. Y. Ting) will cover the sensitivity of these measurements to changes in pressure and temperature. In conclusion, trade-off factors for choosing various hydrophone materials will be suggested.