Highly ordered hydrogen-terminated silicon surfaces are ideal testing grounds for molecular electronics. However, upon formation of these surfaces it is inevitable that some surface sites are not capped by hydrogen. These remaining dangling bonds can interfere with the chemical and electronic properties of nanostructures formed on the silicon surface. In this work, using scanning tunneling microscopy, high resolution electron energy loss spectroscopy and ab initio computational methods, we explore two chemical approaches to refining the hydrogen termination process. We investigate the utility of diimide (N2H2) and N,N-diethylhydroxylamine (DEHA) as hydrogen atom sources that have the ability to cap dangling bonds. (C) 2007 Published by Elsevier B.V.