The Ostwald coefficients L(2,1) of dichlorodifluoromethane (CCl2F2) (Freon-12), chlorotrifluoromethane (CClF3) (Freon-13), tetrafluoromethane (CF4) (Freon-14), and methane (CH4) dissolved in seawater were measured at four temperatures in the range 288-303 K and at a partial pressure of gas of 101.325 kPa. A computer-controlled version of the Ben-Naim/Baer apparatus was used, and the precision of the measurements was on the order of 1.0% or better.