Nanosphere lithography (NSL) has been proved to be an inexpensive, inherently parallel, high-throughput, and materials-general technique for the fabrication of ordered nanoparticle arrays. In this work, we present the fabrication of large-area and exclusively single layer polystyrene colloidal crystal using an air/water interface self-assembly method. The interstice size in the floating colloidal monolayer can be manipulated by a subsequent in-situ annealing with a saturated organic solvent vapor. As a result, large-area, transferrable, and high-crystalline-integrity colloidal masks with controllable interstice sizes for NSL application are achieved. (C) 2012 Elsevier B.V. All rights reserved.