A canister for absorption of fuel vapors from a fuel tank, includes a hollow body defining an internal chamber containing absorbent material, a first opening communicating with a tank vent conduit, a second opening vented towards the atmosphere, and a third opening communicating with a conduit connected to an engine intake manifold. The canister body has outer and inner side walls parallel to and spaced apart from each other, and defining therebetween a thermally insulating interspace extending continuously for the whole circumferential extension of the outer side wall, on all sides of the canister body, whereby said thermally insulating interspace surrounds the internal chamber and promotes saving of heat generated inside the internal chamber in the absorption operating mode, during an engine inoperative stage, so as to improve canister scavenging efficiency during a subsequent stage wherein the scavenging operating mode is activated, when the engine is operative.