The research was carried out in the Laboratory of Seeds Analysis of the Crop Science and Plant Breeding Department of the Faculty of Agriculture/UNESP, Botucatu, SP, Brazil, with the purpose of studying the effects of some factors that can affect the results of the electrical conductivity test, for evaluating the vigor of peanut seeds (Arachis hypogaea L.). The studied factors were: initial moisture content of the seed and imbibition period. The treatments were set in a completely randomized design. Three seed lots of cv. Tatu (sieve 20 = 7.94mm), with differents physiological quality were utilized with three initial moisture content adjusted to approximately 5%, 7% and 9%. The electrical conductivity was evaluated after eight imbibition periods (3, 6, 9, 12, 15, 18, 21 and 24 hours). Four replicates of 25 seeds and temperature of 20°C were employed for each imbibition period. The reading of electrical conductivity was done by conductivimeter and the results were expressed as µS/cm/g. Under tested conditions, it can be concluded that: the initial moisture content of seeds affects the results of electrical conductivit; the period of seeds imbibition can be reduced until three hours for this evaluation.