Аннотация:The present letter demonstrates a simple method to characterize the molecular electron spin qubits, for which a large number of chemical compounds with non-zero spin have been proposed. The method is based on calculating the value of π using a one-qubit protocol based on obtaining and processing Rabi oscillations. It was implemented using a model system of a Finland trityl radical with an electron spin S = 1/2 and a pulsed electron paramagnetic resonance spectrometer. As a result, the value of π was obtained with an accuracy of two decimal places, and an analysis of statistical and systematic errors was carried out.