Spectroscopic ellipsometry is a non-destructive optical technique that measures changes in the amplitude and phase of polarized light after interaction with a material, providing direct access to its dielectric function and related optical properties. In this work, we investigate cadmium diarsenide (CdAs2), a recently identified non-magnetic chiral crystal with an interesting topology. Such materials form a new class of systems that can host Kramers-Weyl fermions, through the interplay of structural chirality, spinorbit coupling (SOC) and time-reversal symmetry, which makes their optical characterization particularly relevant. This research combines spectroscopy ellipsometry with polarized transmission measurements to study CdAs2 along two crystallographic directions over a broad spectral range (near-, mid-, and far-infrared) and across temperatures from 10 to 300 K. This joint approach enables the extraction of the optical conductivity and phonon parameters, and the temperature dependence of the optical band gap. Comparison with previous reflection measurements performed in our laboratory provides a more complete picture of the electronic and optical properties of the sample.