We found that under laser desorption and ionization conditions, quercetin, belonging to the flavonol family, undergoes a decay, which occurs through a photoinduced reaction followed by dimerization of the forming biradical and by the subsequent fragmentation of the dimer. Naringenin, belonging to the flavonone family, also undergoes similar fragmentation, but owing to the lack of conjugation in the C ring, the forming biradical particle is not capable of further dimerization in the same way as observed for quercetin because of its low stability.