Abstract: A cooling device for quenching hot, highly corrosive combustible gases containing chlorine and hydrogen chloride comprises an elongated steel vessel having rounded top and bottom end portions, an inlet connection on the top end portion, a plurality of inclined connections in the top end portion to facilitate injection of quenching liquid, a lateral outlet connection in the lower third of the steel vessel for quenched combustion gases and quenching liquid, an axial outlet connection on the bottom end portion of the steel vessel for cleaning purposes and also providing an outlet for the quenching liquid, an acid-resistant hard rubber lining extending over the interior surfaces of the steel vessel and all connections, an acid-resistant ceramic lining on the hard rubber lining, and a refractory lining in the upper portion of the steel vessel on the acid-resistant lining.