Silicene, a silicon equivalent of graphene, is a newly synthesized nanostructure with unique features and promising potential. Using density functional theory, the geometries and energetics of partially hydrogenated silicene (hydrogenation ratios between 3.1 and 100 atom%) are calculated. We find that the hydrogenation energy increases with the hydrogenation ratio, reaching 3.01 eV/H for complete hydrogenation. Molecular dynamics simulations reveal the stability of the adsorption configurations. Our results show that partial and patterned hydrogenation, achievable through exposing silicene to hydrogen gas with various densities and/or masking techniques, provide the attractive possibility of metal/semiconductor/insulator functionality within the same silicon nanosheet. (C) 2011 Elsevier B.V. All rights reserved.