The invention refers to a device for collecting liquid from exhalation gas from a patient. The device includes a first pipe conduit (5, 8) for the supply of inhalation gas to the patient, a second pipe conduit (6, 9) for the removal of exhalation gas from the patient and a container device (1) for collecting liquid from the exhalation gas. The container device includes a first space (2), which forms a portion of the first pipe conduit (5, 8) and through which the inhalation gas thus flows, and a second space (3), which forms a portion of the second pipe conduit (6, 9) and through which the exhalation gas thus flows. The second space (3) is arranged to receive the collected liquid. The first space (2) is separated from the second space (3) by means of a wall member (4), which has a good thermal conductivity and permits transfer of heat from the exhalation gas to the inhalation gas.