A pharmaceutical composition, intended particularly for potential administration and for treatment of tumor diseases sensitive to oxaliplatinum, comprises oxaliplatinum as the active compound, a pharmaceutically acceptable aqueous solvent and a stabilizing agent in stabilizingly effective amount. The stabilizing agent includes at least one compound selected from the group consisting of acids derived from neutral alcoholic sugars, lactones of these acids and salts of these acids. In a method of producing such a pharmaceutical composition, oxaliplatinum is dissolved in an aqueous solvent, whereupon to the obtained oxaliplatinum solution is added at least one acid derived from a neutral alcoholic sugar and/or at least one lactone of these acids and/or at least one salt of these acids, and optionally the pH value of the solution is adjusted by addition of an alkali metal hydroxide and/or an alkali earth metal hydroxide to pH 3.5-6.5, whereupon the obtained solution is sterilized and filled into individual package units and optionally inertized with nitrogen or argon.