Nickel-iron codeposition was studied by the method of electrohydrodynamic (EHD) impedance spectroscopy. Experiments were conducted in both the potentiostatic and galvanostatic modes. Low-frequency asymptotes of the phase shift of the two modes are in agreement with steady-state behavior. Changes in the spectra with agitation, bath chemistry and applied current density are presented. Simulations from a previous competitive adsorption theory applied now to EHD impedance are compared to the experimental data. The dependence of the spectra on experimental parameters is in fair agreement with model predictions. The model is able to predict a unique feature of the spectra; however the simulated variations in the EHD spectra are not completely consistent with experiment.