The present invention relates to a medical solution, a method for producing said medical solution, a multi-compartment bag containing the medical solution as well as use of said medical solution. According to the invention the medical solution comprises a first single solution comprising bicarbonate and carbonate in such proportions that the partial pressure of carbon dioxide, CO.sub.2, in the first single solution is of the same order of magnitude as the partial pressure of carbon dioxide, CO.sub.2, of the atmosphere. The medical solution further comprises a second single solution comprising an acid. Said first and second single solutions are, after terminal sterilization and up on use, to be mixed to form a final solution. Said second single solution has a pH of 1.0-1.5, and said final solution has a pH of 7.0-7.6.