The capital of Tajik ASSR was in Dyushambe (today's Dushanbe). In October 1929, under the initiative of Shirinsho Shotemur, the Tajik ASSR was transformed into a full-fledged Soviet Socialist Republic and became Tajik SSR, which additionally absorbed the Khujand region (today's Sughd Province in northern Tajikistan) from Uzbek SSR. The capital Dyushambe was renamed Stalinabad in honor of Joseph Stalin.
References
B. A. Antonenko, ed. (1983). History of Tajik SSR (in Russian). Dushanbe: Maorif Publ. House.