In-situ formed AlN hollow sphere reinforced Al matrix syntactic foam parts have been fabricated by metal injection moulding, partial nitridation and a subsequent "open-closed pore transformation" without using pre-fabricated ceramic hollow spheres. The in-situ Al matrix systactic foams feature highly controllable pore size of <20 mu m and exhibit high strength of similar to 200 MPa, which is superior to conventional Al matrix syntactic foams having pre-fabricated ceramic hollow sphere reinforcements. (C) 2012 Elsevier B.V. All rights reserved.