Calcium was removed from Tunçbilek and Soma-Merkez subbituminous coals and Seyitömer, Muğla-Yatağan and Bolu-Göynük lignites with dissolved COj technique. The effect of pretreatment on the liquefaction yield was investigated. With this technique 82.4 % removal of the ion exchangeable and 45.1 % removal of the nonexchangeable calcium were reached. Pretreating the coals with dissolved CO? had an adverse effect on Bolu-Göynük lignite and resulted in decreased liquid product yield while for the rest of the samples tested 8.9- 27.7 % increase were observed in tetraline soluble fractions.