Ag3CUS2, nanocages were successfully fabricated for the first time via a convenient ion-exchange route by Ag+ reacting with Cu7S4 18-facet hollow nanopolyhedra. The average size and shell thickness of Ag3CUS2 nanocages were around 400 and 30 nm, respectively. Room-temperature response Of Ag3CUS2 nanocages to ammonia was investigated by photoluminescence-type sensor. Sensing results suggested that these hollow-structured Ag3CUS2 exhibited better performances including higher sensitivity, shorter response and recovery time than their rod-shape counterparts. A possible hole trapping mechanism was proposed. (C) 2009 Elsevier B.V. All rights reserved.