The structural, optoelectronic and magnetic properties of the Half-Heusler (HH) compounds QEuPa (Q ¼ Ba, Be, Mg, Sr) in the ground state are investigated from the first principles calculations. Stable optoelectronic and magnetic properties of HH compounds are calculated by the FP-LAPW method implemented in the WIEN2k software. The strong correlation between the Eu/Pa f-states is taken into account when studying electronic properties such as the band structure and density of states (DOS). Based on the band structures of the considered compounds, it can be concluded that they are metallic. The dielectric function ε (ω) obtained for QEuPa HH compounds is used to study optical dispersion and absorption. QEuPa compounds absorb the maximum number of incoming photons in the infrared (IR) region. Significant magnetic moment occurs in these compounds due to the splitting of the Eu-4f7, Pa-5f2 and Pa-6d1 localized orbitals.