Abstract. An electrochemical hydrophone based on the principles of molecular electronic transfer (MET) has been described. The paper presents theoretical and experimental results for the sensitivity and the level of self-noise determination for the MET hydrophone (METH) in the frequency range of 0.02–200 Hz, which determines the fields of acceptance of the devices being developed. An experimental model has been developed by using a force-balancing feedback. Different methods and techniques for its calibration have been developed. The experimental device with 0.75 mV Pa⁻¹ sensitivity flat in the frequency band 0.02–200 Hz has been presented. It has been demonstrated that in the ultra-low-frequency range METH noise could be much lower than the standard Wenz noise model. Easy to produce, cheap and suitable for mass production, the MET hydrophone could be in demand in marine and land acoustic research.