B atoms and BH radicals could be identified by laser-induced fluorescence when B2H6/He/H-2 mixtures were activated on heated tungsten wires. The densities of these radical species increased not only with the wire temperature but also with the partial pressure of H-2. The densities in the presence of 0.026 Pa of B2H6 and 2.6 Pa of H-2 were on the order of 10(11) cm(-3) both for B and BH when the wire temperature was 2000 K. Densities in the absence of a H-2 flow were much smaller, suggesting that the direct production of these species on wire surfaces is minor. B and BH must be produced in the H atom shifting reactions, BHx + H -> BHx-1 + H-2 (x = 1-3), in the gas phase, while H atoms are produced from H-2 on wire surfaces. The B atom density increased monotonously with the H atom density, while the BH density showed saturation. These tendencies could be reproduced by simple modeling based on ab initio potential energy calculations and the transition-state theoretical calculations of the rate constants. The absolute densities could also be reproduced within a factor of 2.5.