Louis Kahan's work is represented in the following public Collections:

All State Galleries of Australia
Australian National Gallery
Australian National Portrait Gallery
Museum of Democracy at Old Parliament House, Canberra
National Library of Australia
Parliament House Art Collection, Canberra
Sydney Opera House Collection
S. H. Ervin Gallery, Sydney
State Library of Victoria
Town Hall Gallery, Victoria
Victorian Arts Centre, Melbourne

Regional Galleries in:
Albury, Ararat, Ballarat, Bendigo, Benalla, Devonport, Geelong, Hamilton, Horsham, Launceston,
McLelland Art Gallery and Sculpture Park, Mornington Peninsula Art Centre, Mosman, Newcastle,
New England, Rockhampton, Warnambool, Caulfield Art Centre, Melbourne

Universities of Melbourne, Latrobe, Deakin, Edith Cowan, Flinders, Western Australia, Sydney, Monash, Murdoch, Queensland, Canberra, Jerusalem, Texas and Pennsylvania, Colleges of Advanced Education in Canberra and Melbourne, Charles Sturt University, University of Western Sydney, University of South Australia

Queen's College Chapel, Melbourne (stained glass windows)
The Great Synagogue, Sydney (stained glass windows)
St Peter's Church, Eastern Hill, Melbourne (stained glass windows)
Kew Synagogue, Melbourne (stained glass windows)

International:
Albertina Museum, Vienna
British Museum, London
Bibliothèque Nationale, Paris
Dunedin Art Gallery, New Zealand
Musée d'Art Moderne de la Ville de Paris
Musée de la Marine, Paris
National Army Museum, London
National Portrait Gallery, London
Portland Art Museum, Oregon
Red Cross Museum, Washington
US Army Centre of Military History, Washington
US Military Academy, West Point, New York
Victoria and Albert Museum, London
Worcester Foundation, Massachusetts

National Portrait Gallery, Canberra
https://www.portrait.gov.au/people/louis-kahan-1905

Museum of Democracy at Old Parliament House, Canberra
https://www.moadoph.gov.au/blog/hawke-and-keating-portraits-find-a-permanent-home/

National Gallery of Victoria:
https://www.ngv.vic.gov.au/explore/collection/artist/3677/

Art Gallery of NSW
https://www.artgallery.nsw.gov.au/collection/works/?q=louis+kahan

National Library of Australia:
https://catalogue.nla.gov.au/Search/Home?lookfor=louis+kahan&submit=Submit+search+query

State Library of Victoria:
http://search.slv.vic.gov.au/primo-explore/search?query=any,contains,louis%20kahan&tab=default_tab&search_scope=Everything&vid=MAIN&facet=tlevel,include,online_resources&offset=0

British Museum:
https://www.britishmuseum.org/collection/search?keyword=louis&keyword=kahan