A mobile heating device operated with liquid fuel is provided, having: a combustion chamber (2) comprising a combustion air inlet (3), wherein the combustion chamber (2) adjacent to the combustion air inlet (3) comprises a widening portion (20) the cross-section of which widens with increasing distance from the combustion air inlet (3) and in which in operation combustion air and fuel are converted in a flaming combustion; a fuel supply which is arranged such that fuel is supplied into the widening portion (20); and an air guide device (6) being adapted to feed combustion air into the widening portion (20) with a flow component directed in the circumferential direction such that an axial recirculation region forms in the widening portion (20) in which gases flow in the direction towards the combustion air inlet (3) oppositely to a main flow direction (H).