Hundreds of people are expected at the remote East Coast settlement of Te Araroa to mourn the passing of Ngati Porou kaumatua and Maori language advocate Te Kapunga Matemoana "Koro" Dewes.

Mr Dewes is lying in state at Hinerupe Marae after he died at his sister's home in the township on Tuesday.

He was 80 years old.

Known for his historical knowledge and skill as an orator, Mr Dewes was a pioneer in Maori education and at the forefront of the Maori language revival in the 1960s and 1970s.

Born in 1930, he went to Horoera Native Primary School, and won a government scholarship to attend Wesley College near Pukekohe in 1944.

He became the school's dux and head prefect, and went to Ardmore Teachers College in 1949.

After teaching adult education classes at the University of Auckland, Mr Dewes began lecturing in 1966 at Victoria University in Wellington, where his advocacy for the language helped extend the courses so students could complete a degree major in Maori.

His masters thesis, which focused on Ngati Porou composer Henare Waitoa's work, was submitted in the Maori language in 1972, making him the first person to present his thesis without an English translation.

Mr Dewes left Victoria University in 1976 and returned to the East Coast to farm. He later helped form Te Runanga o Ngati Porou.

His close relative Dr Apirana Mahuika told Radio Waatea that Mr Dewes came from senior genealogical lines in Ngati Porou that include Te Whanau a Rakairoa, Te Whanau a Hunaara, Te Whanau a Hinerupe, Te Whanau a Te Aopare and Te Whanau a Tuwhakairiora.

"For that reason I think that he found leadership an easy take and it wasn't something that he learned but it's something he was born into and he handled it with great acclaim," Dr Mahuika said.

Maori Affairs Minister Pita Sharples said Mr Dewes' command of oral history and literature and prowess in debate were awe-inspiring.

Dr Sharples said Mr Dewes was a partisan rather than a diplomat, who inspired commitment and dedication to Maori language issues among a generation of younger leaders.

"We must acknowledge the seminal contribution made by Koro Dewes, who established the philosophical and political foundation for so much of what has followed," he said.

"Koro has been an inspiration for language activists from every iwi, and for indigenous peoples around the world."

Mr Dewes, who was was awarded an honorary doctorate of literature by Victoria University in 2004, is survived by his children Cathy, Whaimutu and Campbell.

His tangi is to be held tomorrow at 11am before he is buried at Tangata Hapuku urupa in Horoera.