BCxNy films were produced from single‐source precursors in a chemical vapor deposition process. The boranes were introduced as precursors at low pressure conditions and at a temperature of 700 °C, whereas the borazine was handled at 400 °C and with a plasma enhancement at an electrical power input of 40 W. Additionally, as inert or reactive gases, H2, He, N2, and NH3, respectively, were used. The films deposited on Si(100) substrates were chemically characterized by X‐ray photoelectron spectroscopy and by synchrotron radiation‐based total‐reflection X‐ray fluorescence combined with near‐edge X‐ray absorption fine structure and quantified elementally by energy‐dispersive X‐ray spectroscopy. The results are critically compared. With the application of boranes without NH3, compounds with a dominating carbidic character were identified, whereas with the addition of NH3 to the boranes, a nitridic character was prevalent. In case of using borazine for the synthesis, the nitridic character was found at the application of all auxiliary gases. For both groups stoichiometric formulas derived from energy‐dispersive X‐ray spectroscopy are proposed: B3.5–4C4N2–2.5 for the carbidic region and B3.5C1.5N5 for the nitridic region. Copyright © 2012 John Wiley & Sons, Ltd.