IPMCs are electroactive polymers which can be used both as sensors and as actuators. The modelling of IPMC transducers is an open issue relevant to the development of effective applications. A multiphysics model of IPMC actuators is here implemented. It integrates the description of the electrical, mechanical, chemical and thermal coupled physics domains in a unique solution and, as a novelty, it allows the study in the frequency domain and the comparison with experimental response of the IPMC device. The IPMC white box modelling requires several macro- and microscopic parameters, not always accessible via theoretical approaches or experimentation. This work presents a new model optimization procedure which integrates Nelder-Mead simplex method with the COMSOL Multiphysics® models. The proposed procedure uses experimental data and fits model simulations to IPMC real behavior for microscopic parameters’ identification. The model is developed for IPMCs with ethylene-glycol as the solvent