A Langmuir monolayer of octadecylamine (ODA) in the presence of aqueous HAuCl4 subphase produces nanoparticles/nanocrystals of Au at the air-water interface. Au-attached monolayer films were deposited at a constant surface pressure (pi(T)) of the ODA monolayer but at different times after reaching the pT. Xray reflectivity analysis gives the out-of-plane structures of the deposited films and shows time dependent growth behavior of Au adsorption below the ODA monolayer. Atomic force microscopy, scanning electron microscopy and X-ray diffraction analysis mainly shows that the worm-like Au nanoparticles become globular and with time gets crystal structures, which are effectively disc-like. (C) 2011 Elsevier B. V. All rights reserved.