Voltammetric peak of the adsorbed electroactive system may be expressed by a parametric equation; no exact explicit relation is achievable. Present work describes an approximate algorithm (Lorentzian-Gaussian algorithm [LGA]) for the computation of voltammetric peak of diffusionless system with high precision. This algorithm may be used for calculation of voltammetric peaks of adsorbed species; redox behavior of mixed ionic-electronic conductors (Prussian blue, electroactive polymers, etc) can also be covered by LGA if diffusion and charge transfer does not impede the process. This algorithm can be useful in computer simulation of mass transfer in thin films of Prussian blue and other mixed ionic-electronic conductors. Despite being an approximate algorithm, LGA has a remarkable accuracy. Unfortunately, this accuracy has been achieved at the expense of simplicity: LGA makes use of nine adjustable coefficients.