A questionnaire composed of two chemical equations has been administered to 203 second form scientific pupils from 15 Bunia schools in the Democratic Republic of the Congo in order to point out the errors they make in the equilibration of the redox reactions and identify the frequent errors. The obtained results, after the present study have revealed that the committed errors in the redox oxidation equilibration by these pupils are: the calculation of the stage oxidation, the oxidant identification and the reducer, the writing of redox couples, the half-equation redox writing, the reactionary area identification, the calculation of the least common multiple, the addition of the redox half-equation and the stoichiometric coefficient writing. By submitting these results to the Chi-Squared test, it has been found that the observed difference between the revealed error frequencies is very significant because Χ2cal = 327,40 ˃ Χ2tab 5% = 14,07. Thus, the most frequent errors are the oxidation numbers bad calculation (47, 78%), the confusion between the oxidant and the reducer (16, 26%) and the bad writing of the half-equation reduction oxidations (26, 11%). Teachers should, therefore exploit correctly the school books and the necessary procedures for the equilibrium of a redox reaction, but also find new methods to teach well the equilibration steps of an oxidation reaction and the reducer.