A simple procedure has recently been suggested (T. Pajkossy, Electrochem. Comm. 90 (2018) 69) by which various types of voltammograms, above all cyclic voltammograms, pertaining to partially diffusion controlled charge transfer reactions can be analysed. Using this procedure, from voltammograms taken with varied scan-rates or other-than-triangular waveforms two scan-rate independent, hysteresis-free functions can be calculated. One of them is the diffusion-free polarization curve; the other the semiintegrated form of the reversible voltammograms. Here we show the underlying theory in details, along with numerical simulations to highlight important properties of the transformation. The theory opens a new route for the determination of charge-transfer rate coefficients of quasi-reversible redox systems. (C) 2018 Elsevier Ltd. All rights reserved.