GSTU is the one and only largest and prestigious organization of Government School Teachers in Kerala. It is the organization of Primary Teachers,High School Teachers, Language Teachers, Higher Secondary School Teachers, Vocational Higher Secondary School Teachers,TTI Teachers,DIET Lecturers,AEOs,HMs and Principals of Higher Secondary Schools,DIETS and DEO's.
Shri. A.K Antony, then President of Kerala Pradesh Congress Committee inaugurated the first session of GSTU on the 14th of August 1991 at Rajadhani Auditorium, Thiruvanathapuram. It is the amalgamation of three categorical teachers' organizations in Govt.sector, namely Kerala Govt. Primary Teacher's Union(KGPTU), Govt. Graduate Teacher's Organization(GGTO), and Sarkar School Bhashadhyapaka Union(SSBU).Its headquarters is at Thiruvananthapuram situtated at Unni's Lane, Pulimood, Thiruvananthapuram-1 Km walking distance from Govt.Secretariate. GSTU is affiliated to all India Federation of teachers Organizations(AIFTO)and Education International(EI).