A study has been made on the influence of temperature during flotation of the celestite and calcite mineral species, using sodium oleate as the collector and quebracho as the depressant, for a particle size ranging between 80/100 A.S.T.M. mesh (177/149 mu m). The experiments were conducted on pure minerals in a thermostatted Hallimond tube with working temperatures between 293 and 323 K. Results indicate that celestite can be depressed during flotation with sodium oleate due to the action of quebracho, although when the temperature in the bath is increased, the depressor action is slightly inhibited, thus increasing recovery of the mineral. The results for calcite show similar findings, although with a less pronounced depressor effect due to quebracho.