Somdet (Thai: สมเด็จ, pronounced [sǒm.dèt]) is a district (amphoe) in the northeastern part of Kalasin province, northeastern Thailand.

Neighboring districts are (from the southeast clockwise): Huai Phueng, Na Mon, Mueang Kalasin, Sahatsakhan, and Kham Muang of Kalasin Province and Phu Phan of Sakon Nakhon province.

The minor district (king amphoe) Somdet was created on 16 August 1964, when the three tambons Somdet, Mu Mon, and Saeng Badan were split-off from Sahatsakhan district.

[2] The district is divided into eight sub-districts (tambons), which are further subdivided into 91 villages (mubans).

This Kalasin Province location article is a stub.