We have deposited p+ a-Si, C: H films by reactive magnetron sputtering from boron doped target with 1 at.% B. We have investigated the influence of H2 pressure on the electrical and microstructural properties of the doped a-Si, C: H films. The boron concentration in the film is ∼2-4×1020cm-3. The incorporation of B atoms decreases by a factor of 2 at the highest H2 pressure. We have obtained films of Tauc bandgap ∼1.8-1.84eV with dark conductivity 2-8×10-6ω-1cm-1, thermal activation energy ∼0.28-0.33eV and ημτe ∼1-3×10- 8cm2/V. This result is comparable with glow discharge B doped a-Si, C: H film. We discuss the film microstructure, as reflected in infra-red & thermal H evolution spectra, vs. the absolute composition of sputtered boron doped a-Si, C: H films.