The AGILE Mini-Calorimeter (MCAL, with total on-axis radiation length 1.5 X0) comprises 2 orthogonal planes each consisting of 16 CsI(Tl) bars. Its primary purpose is the energy determination of gamma-rays detected by the Gamma-Ray Imaging Detector (GRID) Tracker (energy range 30 MeV–50 GeV). In addition, the MCAL is capable of independently triggering and detecting gamma-ray bursts and other impulsive events in the energy range 0.25–250 MeV. A MCAL prototype, comprising 8 CsI(Tl) detector elements, was tested both with laboratory sources and with charged particles (p=1 GeV/c) during an AGILE Beam Test carried out in November 2000 at the CERN T11 beamline (East Hall, CERN PS). The test setup included a prototype of the electronic chain. A prototype of the digital data acquisition chain, which will be the baseline of the payload Electronic Ground Support Equipment, was also built and tested. We present the preliminary results of this test campaign dedicated to characterizing the detector unit and electronics.