Apparatus for coupling a pour spout fitment to a container comprising: - a structure, - a mobile arm, associated with said structure and tilting with respect to the latter about an oscillation axis; - a support for a pour spout fitment, associated with said mobile arm and slidable along a translation direction which is transverse to said oscillation axis; - a welding head adapted to abut against a wall of said container, associated with said structure and slidable with respect to the latter in a welding direction, transverse to said oscillation axis; - a feeder of pour spout fitments, associated with said structure and equipped with a power head adapted for coupling a pour spout fitment to said support; - first motor means connected to said structure and said mobile arm to oscillate said mobile arm about said oscillation axis, between - a loading position, in which said support is facing said power head for receiving a pour spout fitment, and - an insertion position in which said support is spaced apart from said welding head and aligned to the latter with respect to said translation direction, and said translation direction is parallel to said welding direction; - second motor means connected simultaneously to said support and to said welding head to actuate a simultaneous sliding of said support, in said translation direction, and of said welding head, in said welding direction, between - said insertion position; - and a welding position in which, in use, said pour spout fitment and the wall of said container are pinched between said welding head and said support; characterized in that said support for a pour spout fitment is slidable with respect to said mobile arm along said translation direction, and in that said mobile arm is provided above said welding head. - a structure, - a mobile arm, associated with said structure and tilting with respect to the latter about an oscillation axis; - a support for a pour spout fitment, associated with said mobile arm and slidable along a translation direction which is transverse to said oscillation axis; - a welding head adapted to abut against a wall of said container, associated with said structure and slidable with respect to the latter in a welding direction, transverse to said oscillation axis; - a feeder of pour spout fitments, associated with said structure and equipped with a power head adapted for coupling a pour spout fitment to said support; - first motor means connected to said structure and said mobile arm to oscillate said mobile arm about said oscillation axis, between - a loading position, in which said support is facing said power head for receiving a pour spout fitment, and - an insertion position in which said support is spaced apart from said welding head and aligned to the latter with respect to said translation direction, and said translation direction is parallel to said welding direction; - a loading position, in which said support is facing said power head for receiving a pour spout fitment, and - an insertion position in which said support is spaced apart from said welding head and aligned to the latter with respect to said translation direction, and said translation direction is parallel to said welding direction; - second motor means connected simultaneously to said support and to said welding head to actuate a simultaneous sliding of said support, in said translation direction, and of said welding head, in said welding direction, between - said insertion position; - and a welding position in which, in use, said pour spout fitment and the wall of said container are pinched between said welding head and said support;