A common phenomenon that takes place in bottled extra virgin olive oil (EVOO) is the photooxidation of its pigments, especially chlorophyll, which acts as a singlet-oxygen sensitizer. This translates into a severe decrease of quality, potentially leading to oxidized and rancid olive oils by the time they reach to the consumers. In this current research, the photochemical degradation has been monitored for 45 days in binary mixtures of four monovarietal EVOOs (Arbequina, Hojiblanca, Cornicabra, and Picual) through UV-Visible spectroscopy. A multilayer perceptron-based model was optimized to estimate the photodegradation suffered by the samples, in terms of photodegradation time, relying on the spectroscopic information gathered and attaining an error rate of 2.43 days (5.3%) in the determination of this parameter. (C) 2015 Elsevier B.V. All rights reserved.