Croatian Transmission System Operator's (Croatian: HOPS - Hrvatski operator prijenosnog sustava) mission is electric power system operation and maintenance, electricity transmission, as well as construction and development of electricity transmission network in order to maintain security of supply with minimal costs and environmental protection. HOPS d.o.o. is the sole electricity transmission system operator in the Republic of Croatia, and the owner of the entire Croatian transmission network (400 kV, 220kV and 110kV included voltage levels).