A new geometry is proposed and explored for the investigation of mechanochemical reactions. Typical displacement reactions between an oxide (PbO, CuO, and WO3) and Al as the reducing metal are studied, but instead of starting with a mixture of two powder reactants, Al is introduced in the form of a plate attached to the inside wall of the milling vial and only the oxide is milled in powder form. Consequently, the reaction takes place at the surface of the aluminium plate, where the microstructure can be investigated easily using SEM. The phase composition is followed by XRD. Of the three oxide components, the reaction is the fastest with PbO due to the intense ductile mixing at the interface. The current configuration can be utilized for the investigation of any mechanochemical or mechanical alloying process where at least one of the components can be prepared in the form of a ductile plate that is capable of withstanding the multiple impacts from the milling balls. (C) 2004 Kluwer Academic Publishers.