In this Letter a fast and reliable computational protocol for the calculation of pK(a)* of photoacids is presented. The results obtained for several coumarins indicate that, beyond the obtained numerical accuracy, it is indeed possible to develop a reliable computational procedure for pK(a)* calculation by combining, in a judicious way, a reliable model for the excited states (TD-DFT) with a fast solvent model (PCM). The characteristics of the different components of the model will allow for routine applications to medium and large chemical systems, so that the proposed protocol could nicely integrate experimental analyses.