Process for dehumidifying a moist gas mixture G, in particular moist air, in an apparatus V 1, comprising the steps of: (a) contacting the moist gas mixture G with a liquid absorption medium A VE comprising a mixture of at least one additive selected from the group consisting of compounds of the structure with and at least one salt S selected from the group consisting of Q + A -, Q + (R 1 O) 2 PO 2 -, (Q +) 2 R 2 OPO 3 2-, Q + M + R 3 OPO 3 2-, wherein the liquid absorption medium A VE at least partially absorbs water from the moist gas mixture G, to obtain a liquid absorption medium A VE1 having an elevated water content compared to the liquid absorption medium A VE and a gas mixture G 1 having a relatively low water content compared to the moist gas mixture G, (b) at least partially removing water from the liquid absorption medium A VE1 to obtain a liquid absorption medium A VE2 having a relatively low water content compared to the liquid absorption medium A VE1, wherein the apparatus V 1 at least partially comprises a surface made of a metal material of construction O Al and in the apparatus V 1 at least one of the liquid absorption media selected from the group consisting of A VE, A VE1, A VE2 contacts the surface made of a metal material of construction O Al via at least one contact surface, characterized in that Q + is a dialkylimidazolium cation, wherein A - is an anion selected from the group consisting of R*COO-, R'SO 3 - HSO 4 -, R"SO 4 -, wherein R*, R', R" are each independently of one another an alkyl group, wherein R 1, R 2, R 3 are each independently of one another an alkyl group, and wherein M + is an alkali metal ion, and wherein m and n are independently of each other integral numbers in the range of 0 to 3, and wherein p and q are independently of each other integral numbers in the range of 0 to 30, wherein the sum of p + q is an integral number in the range of 0 to 30, wherein the metal is selected from aluminium, steel, copper, noble metals, titanium. (a) contacting the moist gas mixture G with a liquid absorption medium A VE comprising a mixture of at least one additive selected from the group consisting of compounds of the structure with and at least one salt S selected from the group consisting of Q + A -, Q + (R 1 O) 2 PO 2 -, (Q +) 2 R 2 OPO 3 2-, Q + M + R 3 OPO 3 2-, wherein the liquid absorption medium A VE at least partially absorbs water from the moist gas mixture G, to obtain a liquid absorption medium A VE1 having an elevated water content compared to the liquid absorption medium A VE and a gas mixture G 1 having a relatively low water content compared to the moist gas mixture G, and at least one salt S selected from the group consisting of Q + A -, Q + (R 1 O) 2 PO 2 -, (Q +) 2 R 2 OPO 3 2-, Q + M + R 3 OPO 3 2-, wherein the liquid absorption medium A VE at least partially absorbs water from the moist gas mixture G, to obtain a liquid absorption medium A VE1 having an elevated water content compared to the liquid absorption medium A VE and a gas mixture G 1 having a relatively low water content compared to the moist gas mixture G, (b) at least partially removing water from the liquid absorption medium A VE1 to obtain a liquid absorption medium A VE2 having a relatively low water content compared to the liquid absorption medium A VE1, wherein the apparatus V 1 at least partially comprises a surface made of a metal material of construction O Al and in the apparatus V 1 at least one of the liquid absorption media selected from the group consisting of A VE, A VE1, A VE2 contacts the surface made of a metal material of construction O Al via at least one contact surface, Q + is a dialkylimidazolium cation, wherein A - is an anion selected from the group consisting of R*COO-, R'SO 3 - HSO 4 -, R"SO 4 -, wherein R*, R', R" are each independently of one another an alkyl group, wherein R 1, R 2, R 3 are each independently of one another an alkyl group, and wherein M + is an alkali metal ion, and wherein m and n are independently of each other integral numbers in the range of 0 to 3, and wherein p and q are independently of each other integral numbers in the range of 0 to 30, wherein the sum of p + q is an integral number in the range of 0 to 30, wherein the metal is selected from aluminium, steel, copper, noble metals, titanium.