Laser-induced fluorescence measurements of OH radical concentration are performed in the post-flame gaseous region of a stoichiometric H-2/O-2 mixture combusting at 20 Torr. The measurements are taken near surfaces of three different materials [alpha-alumina (Al2O3), quartz (SiO2), and platinum (Pt) on alumina] at different surface temperatures (from similar to 700 to 1100 K). A comparative analysis of some of the factors affecting OH recombination rate are provided as a function of material and temperature. Of the samples tested, Al2O3 is observed to be the least active whereas Pt on Al2O3 is the most active, with SiO2 at an intermediate level with respect to OH recombination rate on surfaces indicating a quantitative difference between the two relatively inert materials. The result of these differences in recombination rates is that the overall OH number density in the gaseous region within millimeters of the surface was observed to differ by over one order of magnitude between Pt and Al2O3 under nearly identical conditions.