From August 6 to October 14, 2006, gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and fine (PM2.5) particulate-bound mercury (FPM) were monitored atop the Moody Tower at the University of Houston, as part of the Texas Air Quality II Radical Measurement Project (TRAMP). Instrumentation consisted primarily of Tekran mercury sensor models 2537a, 1130, 1135, for the measurement of GEM, RGM, and FPM, respectively. Overall, the mercury speciation measurements showed several very-clean, and several highly-polluted, multi-day periods. The resultant dataset showed GEM concentrations in the range of 1.5 to 5.0 ng m-3. Reactive gaseous mercury varied from below detection limit (BDL) to ~60 pg m-3 with typical afternoon peaks (~3pm). Fine particulate-bound mercury varied from BDL to ~80 pg m-3 with typical early morning peaks (~4am). Highest total atmospheric mercury concentrations occurred during early morning burst events (5-8am) corresponding to shallow (low volume) mixing layer depths, and these concentrations were correlated with carbon monoxide and most volatile organic compounds (except isoprene). RGM and FPM (both water soluble) were virtually absent during strong rain events, and higher RGM concentrations were most often associated with wind directions from the Houston Ship Channel industrial complex.