Parkinson's disease is a chronic neurodegenerative disease and its treatment is aimed at controlling motor and nonmotor symptoms. Pimavanserin is the first antipsychotic with an indication for treatment of hallucinations and delusions in psychoses associated with Parkinson's disease. The aim of this paper was to determine the basis for the development of a new electroanalytical method for the determination of pimavanserin by determining the electroanalytical properties of the drug by cyclic and square-wave voltammetry. Irreversible oxidation of pimavanserin was demonstrated by scanning cyclic voltammograms. The best voltammetric response was obtained by analysing pimavanserin solution on a glassy carbon electrode (GCE) in 0.1 M H2SO4 as the background electrolyte. Modification of GCE by nanomaterials in 0.3% Nafion ethanolic solution yielded even better voltammetric responses due to the increase in the active surface of the electrode, and the electrocatalytic effect of the nanomaterials on drug oxidation. The combination of nanomaterials of graphitized carbon nanotubes and graphene nanoplatelets (1:1) in 0.3% Nafion ethanolic solution gave the best voltammetric responses. Nafion as polymer contributes to better adhesion of nanomaterials to the GCE surface. Also, as cation exchange membrane, it achieves electrostatic interactions with protonated groups of pimavanserin in an acidic medium. The oxidation potential of pimavanserin at such a modified GCE is 1.21 V in 0.1 M H2SO4 under defined optimal conditions of square-wave voltammetry (75 Hz frequency, 20 mV amplitude and 4 mV potential step). There is a possibility of developing a new electroanalytical method for the simultaneous determination of pimavanserin and levodopa as their oxidation potentials do not interfere. However, the combination of pimavanserin and ropinorol is not a good candidate for simultaneous analysis due to overlapping drug oxidation peaks.