Abstract: This invention relates to an apparatus for treating materials.The apparatus comprises a chamber defining a treatment space for treating the textile materials and having an inlet for introducing said textile materials to be treated and an outlet for extracting the treated materials. An endless conveyor traverses the treatment chamber, extending through said inlet and said outlet and conveying said textile materials in said treatment chamber. Means for feeding a treatment agent into said treatment space and means for creating at the inlet and/or said outlet of said treatment chamber, a pressure zone and/or a temperature zone to maintain within the treatment space a gas pressure and/or a temperature higher than that and/or those existing outside said treatment chamber are provided.The apparatus avoids the undersireable flows of gas at said inlet and outlet of said treatment chamber and allows regular treatment operations of the textile materials.