A mathematical model of the compliant tube polymer hydrophone has been developed, which facilitates the evaluation of its low‐frequency electroacoustic sensitivity and maximum operating pressure. Developed by the Naval Underwater Systems Center/New London Laboratory (NUSC/NLL), this type of hydrophone is comprised of the compliant tube (an air‐filled tube of flattened oval cross section and closed ends), a plastic spacer plate which attaches to the flattened surface of the tube, and the piezoelectric polymer (PVF2) film. The PVF2film is bonded to the surface of the plastic plate. It is shown that the sensitivity is enhanced by the use of the spacer, rather than bonding the PVF2film directly to the flattened surface of the compliant tube. Moreover, there is an optimal spacer thickness that maximizes the hydrophone sensitivity. Numerical results are presented for a steel compliant tube polymer hydrophone. The theoretical model has been applied to the NUSC/NLL steel compliant tube polymer hydrophone, with good agreement between the predicted and experimental values for hydrophone sensitivity and maximum operating pressure.