The three-stage KSLV-II NURI rocket emblazoned with the ROK's flag stood on its launch pad at the Naro Space Center ahead of its scheduled 4 p.m. (0700 GMT) blast-off carrying a dummy satellite.
The NURI, or "world", rocket is designed to put 1.5-ton payloads into orbit 600km to 800km (373 miles-497 miles) above the Earth. The ROK's future plans call for launching surveillance, navigation, and communications satellites, and even lunar probes.
Overseen by the Korea Aerospace Research Institute (KARI), the 200-ton rocket was moved to its launch pad on Wednesday and raised into position.
"All preparations like umbilical connection and confidential inspection have been done," the Ministry of Science and Technology said in a statement.
Space launches have long been a sensitive issue on the Korean peninsula, where the Democratic People’s Republic of Korea faces sanctions over its nuclear-armed ballistic missile programme.
The ROK's plans call for launching a range of military satellites in the future, but officials deny that the NURI has any use as a weapon itself.
The country's last such rocket, launched in 2013 after multiple delays and several failed tests, was jointly developed with Russia.
Having its own launch vehicle will give Republic of Korea the flexibility to determine payload types and launch schedules, as well as protect "confidential" payloads such as spy satellites, officials told Reuters.
