Applying femtosecond pump-probe spectroscopy combined with the coincidence detection of photoelectrons and photoions, we have analyzed the energetics of the photoinitiated intracluster reaction in Ba . . . FCH3 on the femtosecond time scale. The rate-determining process of internal conversion from the initially excited (A) over tilde state of the complex to the next lower electronic (A) over tilde' state was directly observed within a few 100 fs after the initiation of the reaction by the 130 fs laser pulse at 618 nm. Thus, the theoretical analysis of the reaction which is based on the calculation of the corresponding potential energy surfaces was confirmed.