An array of eight CsI(Tl) detectors has been set up to measure the light charged particles in nuclear reactions using heavy ions from the Pelletron Linac Facility, Mumbai. The energy response of CsI(Tl) detector to 𝛼-particles from 5 to 40 MeV is measured using radioactive sources and the ¹²C(¹²C, 𝛼) reaction populating discrete states in ²⁰Ne. The energy non-linearity and the count rate effect on the pulse shape discrimination property have also been measured and observed the deterioration of pulse shape discrimination with higher count rate.