In performing its functions HOPS cooperates with all energy market participants in accordance with the regulations in the field of electricity transmission and Croatian Energy Regulatory Agency (HERA).
HOPS cooperates with other European system operators and foreign market participants, as well as with many Croatian and international institutions in the field of electricity transmission, such as European Commission, Energy Community Secretariat and ACER, along with membership organizations such as ENTSTO-E, RGI, Med TSO, etc.