The commissioning phase of the ALPI post-accelerator started at the beginning of 1994 with the installation of the medium beta section ( β = 0.11). Test beams of different injection energies and ion species have been accelerated with ALPI and delivered to the experimental halls. The main components of the post-accelerator, namely the cryogenic plant, the pulsing system, the optical and diagnostic elements for the beam transport, the vacuum, rf and control systems was widely tested under different conditions. The average accelerating field over the 44 installed superconducting lead on copper resonators turns out to be 2.5 MV/m and the phase locking procedure for the 48 resonators (accelerating and buncher cavities) is normally completed in about 10 hours. The overall beam transmission towards the post-accelerator is 70% with the DC beam and up to 50% with the pulsed and accelerated beam with currents on the target of the order of some p nA.