The laminar incompressible flow develops within a channel with two permeable walls which undergo expansion. The flow is injected through the two uniformly porous walls kept at different temperatures. The mathematical model of the problem is obtained by applying mass, momentum and energy conservations. Using the similarity transformation technique, the governing equations give rise to two nonlinear ordinary differential equations. The numerical procedure for solving the differential equations of the problem is detailed. The numerical results are analyzed and the influences of the Reynolds number, the Prandtl number, and the wall moving ratio are discussed. The variations of the velocity distribution, thermal gradients, and pressure gradients are obtained. In particular, when low injection occurs concurrently with high expansion, the reverse flow takes place inside the channel. High injection provides oscillatory pressure gradients under different expansion ratios.