During one of these tribal meeting to discuss new name for Papua in Tobati, Jayapura, he suggested the name from Mansren Koreri myths, Iri-an from the Biak language of Biak Island, meaning "hot land" referring to the local hot climate, but also from Iryan which means heated process as a metaphor for the land that is entering a new era.

[1] He with his brother Markus Kaisiepo then wrote an article in British Columbia Camp newsletter with the title “PAPUA or IRIAN” published on 8 September 1945 to promote its adoption.

[6] Upon release from prison in the year 1961, and during his time as district head in Mimika, Kaisiepo established Irian Sebagian Indonesia (ISI) Party.

To envisage the decolonization of Netherlands New Guinea, President Sukarno made a speech that established the Trikora (Tri Komando Rakyat, "People's Triple Command") on 19 December 1961 in Yogyakarta.

[8] The command's goals were: As a result of this historic address, many Indonesians including exiles from Papua, volunteers from Singapore and Malaya chose to join in organisation called Perintis Irian Barat (PIB), and was organised into volunteer battalions such as Yon Karya Jaya I under Kodam Jaya V, as part of Operation Trikora.

Meanwhile, the Indonesian government would be entrusted with developing the region from 1963 to 1969, and at the end of that year, the Papuans would have to decide whether or not to join Indonesia or remain autonomous.

Because of his disappointment with the Suharto military regime, he would later join the Papuan exile in Wijhe, the Netherlands since 1982, leaving his family in Indonesia and playing an important role in the Free Papua Movement.

[citation needed] During Kaisiepo's term as governor of Irian, he strove to promote Papua as part of Indonesia, by campaigning in all regencies like Merauke, Jayawijaya, Paniai, Fak-fak, Sorong, Manokwari, Teluk Cendrawasih and Jayapura for unification.

This encouraged support within the state for the Act of Free Choice option of unification, as opposed to full independence, despite huge opposition from some Papuan natives.

[11] According to Drooglever, during his time as governor the population of Papuan increased and the education level improved compared with situation under Dutch colonial authority.

On 12 November 1973, he married Maria Magdalena Moorwahyuni, a Christian woman from aristocratic Tjondronegoro family, with her great-grandfather being Bupati of Kudus, Central Java.