Two-color femtosecond pump-probe spectroscopy has been applied to the multiphoton dissociation of NO2 with a time resolution of less than or equal to 350 fs. At laser intensities in the range similar or equal to 3 x 10(12)-2 x 10(13) W cm(-2) and a wavelength of 400 nm, NO2 absorbs three photons before dissociation. Nascent NO A (2)Sigma(+) product in its n(') = 0 and 1 vibrational levels is probed by single-photon fluorescence depletion at 800 nm. Analyses of the ultrafast transient behavior at different intensities leads to an estimate of less than or equal to 600 fs for formation of NO A (2)Sigma(+) n(') = 0 and 1.