Polycrystalline diamond films have been grown by hot filament (HF) chemical vapor deposition on WC-Co bar substrates using different CH4/H-2 source gas mixing ratios and two different total gas pressures. Each substrate was mounted so as to span a range of HF-substrate separations, d(f), (and thus substrate temperatures) and therefore samples a spread of incident gas phase chemistry and compositions. Spatially resolved scanning electron microscopy and Raman analysis of the deposited material provides a detailed picture of the evolution of film morphology, growth rate, sp(3)/sp(2) content and stress with df in each deposited sample, and of how these properties vary with process conditions. The experimental study is complemented by two-dimensional model calculations of the HF-activated gas phase chemistry and composition, which succeeds in reproducing the measured growth rates well. (C) 2011 Elsevier B.V. All rights reserved.