The energy partitioning in photodissociation of n-alkyl iodides has been studied by state-selective photofragment translational spectroscopy combined with a pulsed molecular beam at 304 nm. Translational energies of photofragments are obtained by analyzing the time-of-flights of two product channel iodine atoms, i.e., I( 2 P 3 ) and I * ( 2 P 1 ) for CH 3 I, C 2 H 5 I and C 3 H 7 I. The average energy disposed into the internal mode (E i n t ) of alkyl radicals has shown an increasing tendency from 17% for the I * channel of CH 3 I to 53% for the I channel of n-C 3 H 7 I and is estimated to further increase to 76% for the I * channel of C 4 H 9 I. The methyl radical in CH 3 I photolysis has shown the vibrational excitation in its umbrella mode. The distribution peaks have appeared at ν = 2 for I * and ν = 4 for I product channels, respectively. The observed results are compared with a classical impulsive description dynamics. The energy partitioning is found to be very little dependent on the excitation wavelength for photodissociation all over the A-band region.