Devices and method for warm gas therapy is provided. Device comprises a gas warmer assembly to warm a first gas to a temperature in a first temperature range to obtain warm first gas. The device comprises a first delivery unit that can deliver the warm first gas to a main treatment chamber which encloses a sub-treatment chamber to retain heat therein. A second delivery unit can receive a therapeutic gas from a gas supply. The second delivery unit comprises a first portion and a second portion. The first portion substantially passes through the first delivery unit and therapeutic gas in the first portion is warmed by the warm first gas. The second portion delivers the warm therapeutic gas to a sub-treatment chamber. The sub-treatment chamber encloses a body part of a patient.