Abstract: A method and arrangement for providing an indication of a temperature state of open container bodies during in-line handling. The container bodies are conveyed along a conveyance path, with the openings of the container bodies being freely accessible. A pyro-electric detector is positioned along the conveyance path of the openings facing the conveyance path of the openings. An opening of one of the containers is detected upon reaching a position opposite the pyro-electric detector, and the pyro-electric detector measures heat radiation from the opening detected as having reached the position opposite the pyro-electric detector. The heat radiation measured determines the overall thermal energy content of the open container body as the temperature state thereof.