We deposited CVD diamond films at substrate temperatures T-sub below 600 degrees C using halogen-containing precursor gases. CHF3 and C2H5Cl made possible a significant decrease in T-sub down to 370 degrees C using hot-filament CVD technique. At lower T-sub only amorph-graphitic depositions could be obtained. The lowest substrate temperature for diamond growth T-min depends on the deposition parameters. We find a decrease in this temperature with decreasing carbon content in the precursor gas or decreasing filament to substrate distance. These effects show the influence of both surface diffusion and concentration of radicals in the gas phase near the substrate.