Reproductive aspects (spawning season, size and weight at maturity, and fecundity) of Octopus hubbsorum are reported for Espíritu Santo Island, southern Gulf of California (Mexico). A total of 230 octopuses were captured (46% females and 54% males) between June 2006 and June 2007. The sex ratio was not significantly different from 1:1 (P > 0.05) except in November, when more males were captured than females. Four sexual maturity stages were established for both sexes: immature, maturing, mature, and prespawning (for females) or spawning (for males). The principal spawning season of O. hubbsorum occurred in autumn, when sea surface temperature ranged from 24 to 29 ºC. The size and weight at maturity were 390 mm and 445 g, respectively, for males and 490 mm and 680 g, respectively, for females. The mean potential fecundity was 205,144 oocytes per female and the mean relative fecundity was 309 oocytes per gram of female body weight. Maturing females apparently use substances stored in the digestive gland.