The ß-C3N4 phase should have a tetrahedral (sp3-bonded) structure resulting in C1s and N1s XPS peaks with only one feature at a position defined by the electronegativity of four C---N bonds. In this work we determined the binding energy of the C1s and N1s XPS peaks in melamine (C3N6H6). In this compound the carbon atoms have four bonds with nitrogen atoms (double and two single); the nitrogen atoms have two chemical states: C---N=C and C---N=H2. Since the total number of chemical bonds in this compound is the same as in the hypothetical ß-C3N4 compound, this compound is more suitable as a C1s XPS reference for the ß-C3N4 phase. The binding energy of the C1s and N1s XPS peaks in melamine was determined to be equal to 287.9 and 399.1 eV, respectively. The binding energies were determined relative to the C1s XPS peak for carbon contamination (adventitious carbon).