We present a study of the spectral energy distribution of the peculiar hypergiant IRC+10420. To this end we have collected published photometry of IRC+10420 and obtained some new data, in order to construct the spectral energy distribution and fit it with a radiative transfer model. In addition high-quality ^12CO spectra of the rotational J=1-0, 2-1, 3-2 and 4-3 transitions have been obtained to determine the gas outflow velocity and independently estimate the gas mass-loss rate. The main conclusions from this work are that the photometric changes over the last 20 years indicate that the object has increased in temperature by more than 1000K and that the spectral energy distribution cannot be fitted with a single-shell model without first including a hot component. This hot component is likely to be a circumstellar disc. Finally, we present evidence that IRC+10420 is not a post-AGB star.