Thiol-rich polyhedral oligomeric silsesquioxane (POSS-SH) is prepared via hydrolytic condensation of 3-mercaptopropyl trimethoxysilane (MPTS). Thiol groups on the surface of POSS-SH exhibit strong affinity to mercury species. It is demonstrated to be an efficient sorbent for the adsorption of Hg2+ and CH3Hg+ with sorption capacities of 12.90 and 46.73 mg g(-1) respectively, and sorption efficiencies of 93% and 94% for 0.5 mu g L-1 of Hg2+ and CH3Hg+. This provides a promising material for the removal of mercury from water bodies. The adsorbed mercury species can be readily recovered from the surface of POSS-SH with thiourea (2% (m/v)) as stripping reagent (eluent). By taking advantage of atomic fluorescence spectrometry, Hg2+ is quantified under cold atomization mode while total mercury is obtained by heat atomization mode. This provides an approach for the speciation of Hg2+ and CH3Hg+. With a sample volume of 4.0 mL and an eluent volume of 400 mu L, enrichment factors of 8.9 and 9.3 are achieved for Hg2+ and CH3Hg+ respectively. Linear ranges for Hg2+ and CH3Hg+ are 0.005-2.0 mu g L-1 and 0.01-2.0 mu g L-1, along with detection limits of 2 ng L-1 (3 sigma, n = 11) and 4 ng L-1 (3 sigma, n = 9), respectively. The RSDs for the quantification of Hg2+ (0.1 mu g L-1, n = 11) and CH3Hg+ (0.1 mL(-1), n = 9) are 3.5% and 3.1%. This method is validated by analyzing mercury in a certified reference material (GBW08603, mercury in water). In addition, speciation of Hg2+ and CH3Hg+ in lake and sea waters and the extract of cosmetic are performed, giving rise to satisfactory spiking recoveries. (C) 2013 Elsevier B.V. All rights reserved.