We report on generation and observation of photoacoustic pulses in bismuth thin films using femtosecond reflectivity spectroscopy. Upon photoexcitation of bismuth thin films with a femtosecond laser pulse, hot carriers are created in the optical penetration depth and diffuse into the interior. They scatter off the interface effectively and raise the lattice temperature generating a picosecond acoustic phonon pulse which propagates towards the free surface and modulates the reflectivity. By monitoring the reflectivity change at the surface in real time, we investigate photoacoustic responses as a function of excitation fluence and film thickness.