[en] In this paper, we investigate the transport properties of LiMgX; X = N, P, As half-Heusler alloys using the density functional theory and semi-classical Boltzmann theory based calculations. The electronic structure calculations have been performed within the generalized gradient approximation. The transport coefficients such as electrical conductivity, Seebeck coefficient, electronic thermal conductivity and power factor have been calculated using the semi-classical Boltzmann theory within the constant relaxation time approximation. The electronic structure calculations revealed that these compounds are indirect wide band gap semiconductors. Despite the wide band gaps, these compounds exhibit large values of Seebeck coefficient and power factor thus can be potential candidates for technological applications. Among the studied LiMgX alloys, LiMgN has large power factor of 2.31 × 10¹² W m⁻¹s⁻¹ K⁻² at 1200 K which makes it a possible promising candidate for the thermoelectric applications at high temperatures. (paper)