The invention relates to a method of analyzing a rock sample, comprising:—placing a rock sample (2) containing a first fluid into a cell (1);—feeding the cell (1) with at least one second fluid and withdrawing said second fluid from the cell (1), leaving the rock sample (2) immersed in the second fluid; and—measuring an amount of first fluid spontaneously released from the rock sample (2). The invention also relates to an apparatus adapted for implementing this method.