An apparatus for heat-sealing a lidding film to a supporting element on which a product is present, the apparatus comprising: a structure ; a movement track which is fitted on the structure and which extends between an infeed zone and an outfeed zone; a heat-sealing device which is fitted on the structure , along the movement track , and which comprises a supporting unit and a closing unit ; at least one of the supporting unit and the closing unit being movable, relative to the other, between a home position in which they are at a distance from each other, and an operating position in which the supporting unit and the closing unit are coupled to clamp, in use, the lidding film and a supporting element ; a conveying unit which is configured to support the supporting element and is associable with the movement track for moving on it, conveying the supporting element , from the infeed zone to an intermediate zone at which the heat-sealing device is located, and from the intermediate zone to the outfeed zone; wherein: the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat ; and when the conveying unit is located in the intermediate zone , during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit . a structure ; a movement track which is fitted on the structure and which extends between an infeed zone and an outfeed zone; a heat-sealing device which is fitted on the structure , along the movement track , and which comprises a supporting unit and a closing unit ; at least one of the supporting unit and the closing unit being movable, relative to the other, between a home position in which they are at a distance from each other, and an operating position in which the supporting unit and the closing unit are coupled to clamp, in use, the lidding film and a supporting element ; a conveying unit which is configured to support the supporting element and is associable with the movement track for moving on it, conveying the supporting element , from the infeed zone to an intermediate zone at which the heat-sealing device is located, and from the intermediate zone to the outfeed zone; wherein: the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat ; and when the conveying unit is located in the intermediate zone , during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit . the conveying unit defines a seat for the supporting element and comprises one or more active portions configured to support from below the supporting element positioned in the seat ; and when the conveying unit is located in the intermediate zone , during an activation of the heat-sealing device the one or more active portions couple to the supporting unit to define with it a clamping unit for clamping the supporting element against the closing unit . <EOS>