Abstract: The method for chemical vapor identification using swelling-based sensors uses an apparatus that having a first gas chamber including a gas inlet port for inletting a hydrocarbon vapor to be analyzed; a second gas chamber having a hydrocarbon vapor outlet port for exiting the vapor; a chemical sensor placed inside the first and the second gas chambers; and a thermometer placed inside the first and the second gas chambers for measuring the internal temperature; wherein the second gas chamber is placed at a lower temperature compared with the first chamber; and wherein the first gas chamber is in communication with the second chamber by a pipe for transmitting the hydrocarbon vapor from the first chamber to the second chamber.