 In 1996, Eric Buffetaut, Varavudh Suteethorn and Haiyan Tong named and described the type species "Siamotyrannus isanensis".The generic name is derived from the old Thai kingdom of Siam, and a Latinised Greek "tyrannus", meaning "tyrant", in reference to a presumed membership of the Tyrannosauridae.The specific name is derived from Thai "isan", "northeastern part", referring to the provenance from northeast Thailand.