A series of novel polyhedral oligosilses-quioxane nanofiller compounds functionalized with hydrogen-bond acidic sensor groups was prepared, characterized by IR, H-1-, C-13- and Si-29-NMR, and MALDI-TOF MS, and formulated into polymer coatings for 500 MHz surface acoustic wave sensor platforms. Sensor responses to the explosives simulant dinitrotoluene and to the nerve agent simulant dimethyl methylphosphonate were studied, and the performances of the polyhedral oligosilsesquioxane formulations were compared with those of conventional hydrogen-bond acidic linear surface acoustic wave sensor polymers carrying the same sensor groups. The polyhedral oligosilsesquioxane formulations gave good initial responses to the simulants, maintained 40-65%, of their original response over a period of 6 months and maintained their sensitivity down to a simulant vapor concentration of 1 ppb v. The surface compositions of the surface acoustic wave sensor coatings were characterized by sum frequency generation spectroscopy. (c) 2007 Wiley Periodicals, Inc.