Purpose -Analysis of harmonics propagation in power systems requires information about models of non-linear loads which are the main source of harmonics. The purpose of the paper is to present a method of parameter determination of non-linear loads. Design/methodology/approach -A method of parameter determination of a model has been described in the article. This method has been developed assuming that mathematical description of a non-linear load is known. In order to obtain a harmonic representation of this model for one-phase loads the theory of harmonic balance method has been used. Findings -Parameters of the current or voltage controlled sources can be expressed as a function of any number of voltage or current harmonics. In the case under consideration the network input current is a function of input voltage and its derivatives. Thus, contrary non-linear element with inertialess characteristics, the first harmonic of the current depends not only on amplitude but also on frequency of the voltage across terminals of one-ports. Originality/value -The method presented in the paper enables relatively simple determination of frequency parameters of non-linear models of one-port networks.