Optical properties of two intermetallic compounds TbNiFe and TbNiCo have been studied employing ellipsometry in a spectral range 0.22-15 μm to reveal their characteristic features in comparison with the parent compound TbNi. The electronic structure of TbNiFe and TbNiCo was calculated within the LSDA U method (local spin density approximation with Hubbard U-correction). Based on the calculated electronic structure results, the theoretical optical conductivity was calculated and used to interpret experimental conductivity in the range of interband optical absorption.