| 1974 |
Olav Thon purchases Hotel Bristol |
| 1983 |
Olav Thon purchases Hotell Munch and starts Oslo's first bed and breakfast hotel |
| 1989 |
Rainbow hotels is established and consisted of 11 hotels |
| 1990 |
Enter into collaboration agreement with Rainbow Hotel Sandnes Purchases and opens Rainbow Hotel Gyldenløve in Oslo |
| 1991 |
Purchases Hotel Stefan and Hotel Europa in Oslo |
| 1992 |
Rainbow Hotel Hallingdal becomes part of the chain. Tulip Inn Rotterdam opens |
| 1994 |
Slottsparken Aparments associated with the Rainbow chain Rainbow Hotel Spectrum and Rainbow Hotel Gildevangen opens |
| 1995 |
The first hotels in Bussels; Golden Tulip Brussels Airport and Hotel Bristol Stephanie. Builds Rainbow Hotel Terminus |
| 1996 |
Purchases Summit Stanhope Hotel in Brussels |
| 1997 |
Rainbow Hotel Maritim opens |
| 1998 |
Rainbow Hotel Oslofjord in Sandvika opens Rainbow Hotel Bristol opens Purchases Tulip Inn Brussels Boulevard |
| 2000 |
Rainbow Hotel Nordlys in Bodø opens Rainbow Hotel Vettre in Asker opens |
| 2001 |
Rainbow Hotel Opera in Oslo and Rainbow Hotel Brygga in Tønsberg opens Purchases Thon Conference Gardermoen Park |
| 2002 |
Rainbow Hotel Harstad opens Gausdal hotel and Austlid Fjellstue becomes a part of the Rainbow chain Rainbow Hotel Arena in Lillestrøm opens Takes over Carlton hotel in Lillestrøm (now: Thon Hotel Lillestrøm) |
| 2003 |
Rainbow Hotel Ski opens Rainbow Hotel Wergeland in Kristiansand opens |
| 2004 |
Rainbow Hotel Moldefjord opens Rainbow Hotel Åsgårdstand becomes a part of the chain |
| 2005 |
Takes over Rainbow Hotel Triaden in Lørenskog and Rainbow Hotel Arendal. Purchases Troghatten hotel in Brønnøysund (Now: Thon Hotel Brønnøysund) Rainbow Hotels changes its name to Thon Hotels and divides the hotels into three different concepts; Thon Budget, Thon City and Thon Conference. Collaboration agreement with Thon Hotel Sandviken Brygge in Bergen. |
| 2006 |
Strand Hotel uin Gjøvik becomes Thon Hotel Gjøvik Thon Hotel Gardermoen opens Thon Hotel Linne joins the chain |
| 2007 |
Thon Hotel Hammerfest joins the chain Thon Hotel Oslo Airport opens Thon Hotels starts to certifie the hotels in Norway with Eco-lighthouse |
| 2008 |
Thon Hotel Kautokeino opens Thon Hotel Oslo Panorama opens Thon Hotel Charlottenberg opens (first hotel in Sweden) Vica hotel in Alta joins the chain (Thon Hotel Vica) Highland Hotel and Vestlia Resort in Geilo becomes a part of Thon Hotels |
| 2009 |
Introduces the fourth consept: Thon Resort Thon Hotel Halden opens Thon Hotel Lofoten opens Collaboration agreement with First Hotels Thon Hotel Ullevaal Stadion opens Thon Hotel Kristiansund opens Thon Hotel Torghatten opens |
| 2010 |
Thon Hotel Tromsø opens Thon Hotel Alta opens Thon Hotel Kirkenes opens Thon Hotel Bjørneparken opens Thon Hotel Prinsen in Trondheim becomes a part of Thon Hotels Thon Hotel Sandviken Brygge leaves the chain Thon Hotel Gjøvik leaves the chain |
| 2011 |
Thon Hotel Sandven in Norheimsund becomes a part of Thon Hotels Thon Hotel Backlund in Levanger becomes a part of Thon Hotels |
| 2012 |
Thon Hotel Elverum becomes a part of Thon Hotels Thon Hotel Høvik becomes a part of Thon Hotels Thon Hotel Highland and Thon Hotel Vestlia leave the chain |