Ternary carbides RNiC₂ (R = rare earths and Y) crystallize in the non-centrosymmetric orthorhombic CeNiC₂-type structure, space group Amm2. This family of compounds attracted attention, because of interesting properties such as superconductivity, magnetism, multiple charge density wave (CDW) transitions related to quasi-one-dimensional electronic features, and finally, a complex interplay of CDW order and rare earth magnetism (see Ref. [1] for a review). Here, we report on studies of the crystalline electric field effects in RNiC₂. Single crystal data of thermodynamic bulk properties such as heat capacity and magnetic susceptibility of heavy rare earth RNiC₂ with R = Tb-Tm are complemented with powder inelastic neutron scattering studies of DyNiC₂ and TmNiC₂ conducted at the MAPS instrument at the ISIS neutron spallation source to analyse the crystalline electric field (CEF) splitting in these compounds in terms of a systematic evolution of corresponding universal CEF parameters. The latter are essential to further explore the formation of magnetic ground states of these compounds.