On the basis of a generalization of the single-bond Pauling's equation in solid compounds, a correlation between the optical bandgap and the difference of electronegativity in nitride alloys is derived. The experimental bandgaps of Ga(1-x)AlxN and Ga(1-x)InxN alloys reported in literature, as a function of composition, follow a linear dependence from the square of the difference of electronegativity without the introduction of any bowing parameter. The bandgap value of InN extrapolated according to the proposed correlation is very close to recent theoretical estimates based on density functional theory and to recent experimentally determined values. (C) 2008 The Electrochemical Society.