Mateer is a poet, art critic and practising Buddhist who grew up in an English-speaking family in South Africa and Canada. Prior to being conscripted during 'the State of Emergency' in South Africa, he moved with his parents to Western Australia in 1989 and then to Melbourne in 1998. Mateer graduated with a Bachelor's degree in Fine Arts and Literature from the University of Western Australia.
His poetry has been published and reviewed in journals and newspapers in Australia, South Africa, Indonesia, the United Kingdom and the United States. He has occasionally written in Afrikaans 'in order to examine more fully what it means to be African' (Fremantle Arts Review, Aug/Sept 1994). He was invited to read his work at the International Meeting of Poets in Coimbra, Portugal, at WORDfEAST Singapore, Poetry Africa, the 62nd World Congress of PEN and at the Teater Utan Kayu in Jakarta. Mateer has also read his works at festivals in Australia including Ngara: Living in this Place Now. In 1998-1999 he was the inaugural Writer-in-residence at the Australia Centre Medan in North Sumatra and in the northern hemisphere fall of 2007 he undertook a residency at the Ledig House Writers' Colony, Omi, New York.