Mobile device (10) for heating rooms, comprising radiant elements (12), each provided with two heat-conductor plates (14, 16) associated with each other to define a central portion (18) and connected fluid-dynamically with each other by means of connection elements (20). A heated heat-carrying fluid is able to flow in the central portions (18) and, through the connection elements (20), from one to the other of the radiant elements (12) in order to heat the surrounding room. Each pair of heat-conductor plates (14, 16) comprises lateral walls (22) which are distanced from the corresponding central portion (18) so as to define respective peripheral zones (26). The mobile device (10) also comprises heat-insulating elements (24) able to be applied due to having substantially the same shape so as to cover at least a part of the peripheral zones (26) of the lateral walls (22).