This is the description of an induction diffuser, of the type that is anchored to the ceiling of an enclosed area to diffuse non isothermal air towards the inner space of the enclosed area. It has a truncated cone shape and designed inside in a cylindrical shape so it can be connected to the plenum that feeds the treated air. Inside the plenum there are two sub-casings placed one on top of the other, respectively concentric with each other and with the outer casing. They are joined by the perimeter edge of their larger base with respect to a front closing plate, aided by different sized uprights, aligned according to two circumferential lines, equally spaced at an angle and the front closing plate has a central orifice facing the innermost sub-casing, and has a smaller diameter than the base of the latter. The front plate has been designed with a radially variable thickness.