Femtosecond spectroscopy of aqueous solutions of the four nucleic acid bases adenine, cytosine, thymine and uracil is presented with probing from 282 nm to 750 nm. After two-step excitation at 282 nm part of the molecules returns to the ground state allowing for the determination of the lifetime of the S-1 state yielding values of tau(1) similar or equal to 1 ps for the four bases. The remainder photo-ionize with an ionization yield of 0.7 for adenine, twice as large as for the other bases. The first intermediate is assigned to a (base(+):e(-))-pair with a lifetime of 10 ps for adenine, four times longer than for the other solutions.