Resonant two photon ionization (R2PI) technique was used to obtain the excitation spectrum of the Ba2 molecule. A group of 12 vibrational bands was found in the 740-764 nm region. As a result of mass selective detection, they were attributed unambiguously to the Ba2 molecule. By comparison to recent theoretical calculations, those bands were assigned to the (2)1Sigma+u-X(1)1Sigma+g transition; they may be fitted to give the following vibrational constants (in cm-1): omega"e = 33.2 +/- 0.2, omega"ex"e = 0.5 +/- 0.2, omegae = 65.2 +/- 0.2, and omega'ex'e = 0.4 +/- 0.2. Copyright 1998 Academic Press.