A method for purification of uncatalyzed natural fuels in liquid state from metal ions by removing at least one compound selected from the group consisting of natural occurring contaminating porphyrins, metalloporphyrins, chlorins and naturally occurring degradations products of these compounds, such as petroporphyrins, containing said metal ions from the fuels. At least one hemeprotein in apo-form selected from the group consisting of globins, peroxidases, pyrrolases and cytochromes having high affinity for porphyrins is added to the fuels. The hemeprotein is mixed with the fuels in such a way that the porphyrins is bounded to the hemeprotein. The hemeprotein with bound contaminating porphyrins is removed so as to obtain purified fuels. The invention relates also to the use of at least one hemeprotein selected from the group consisting of globins, peroxidases, pyrrolases and cytochromes having high affinity for porphyrins for the purification of uncatalyzed natural fuels in liquid state from metal ions.