The flavonoids are phenolic substances of low molecular weight, about which are known around 8000 individual compounds. They are abundant in vegetal tissues, apple being one of the most important (particularly its skin). These compounds are characterized to have a high antioxidant activity, which confers to them pharmacological properties useful for the treatment of several diseases. In this work, we make use of a new model chemistry within Density Functional Theory, which is called CHIH-DFT, to calculate the molecular structure of quercetin, as well to predict its infrared and ultraviolet spectra. The calculated values are compared with the experimental data available for this molecule as a mean of validation of our proposed chemistry model. The predicted results are in excellent agreement with the experimental ones.