The reactive wetting process of a flat solid alumina (α-Al2 O3) ceramic surface by metallic aluminum (Al)nanodroplets with different shapes (spherical, cylindrical, and layer) is studied using parallel molecular dynamics (MD)simulations based on a variable charge MD method, with focuses on heat transfer, mass transfer, and the structure of thereactive region at the Al/α-Al2 O3 interface. We find that the diffusion of oxygen (O) atoms from the substrate into thedroplet leads to the formation of a continuous layer of reaction product at the interface. The diffusion length of oxygenatoms into the spherical Al droplet is found to be ~7.3 Å, and the number density of O atoms at the ~5 top layers ofthe substrate decreases substantially. As a result, the structural correlations near the reactive region differ considerablyfrom those in the solid substrate. Heat generated by the exothermic reactions in the reactive region is transferred toboth the substrate and the droplet. The heat transfer is found to be sensitive to droplet shape.