This paper reports the first results obtained on the photodissociation of the isolated PAH cations 12C 24H +12, 13C 12C 23H +12 and 12C 24H +10, using the astrochemistry experimental set-up PIRENEA. The dissociation patterns of these ions involve the loss of pairs of hydrogen atoms. A first interpretation indicates that the -H 2 dissociation path is favoured compared to the -H path in our experimental conditions. These results might have important implications on the formation of H 2 in the interstellar medium.
