Results of a comparative study of pore evolution in nanostructured alumina membranes under annealing in a gyrotron microwave system and in conventional furnace are described. Microwave heating has resulted in an enhanced mass transport leading to reduction in the surface porosity of the membranes. Evolution patterns for the shape of individual pores are discussed and compared for microwave and conventional annealing. The notably different behavior of the pores suggests that microwave radiation provides an additional driving force for mass transport. The experimentally observed enhancement of mass transport appears to be stronger than predicted by the earlier proposed models.