The influence of nitrogen addition on the properties of oxyacetylene flame-deposited diamond has been studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy and cathodoluminescence spectroscopy (CL). A morphological transition reported in earlier work was found to have a major influence on the diamond properties. XRD indicated the presence of a molybdenum carbide layer in between the diamond film and the molybdenum substrate. Thermal stress proved to be the dominant source of layer stress, which in turn was found to be the main cause for the width of the diamond Raman line. In the fraction of the Raman signal that is not due to the diamond Raman peak a drop was observed that can be ascribed to a decrease in the sp2 carbon-related luminescence. The CL measurements showed that, for the present series of samples, blue band A luminescence is stronger from {111} than from {001} facets. Diamond film with the optimal combination of fast growth rate, good surface coverage, high crystalline quality, rather good 〈001〉 texture and zero net stress was grown with 10 sccm of nitrogen.