Si Kai (Thai: สีกาย) is a sub-district (tambon) 18 kilometers east of the provincial capital of Nong Khai in Nong Khai Province, Thailand.
The sub-district is in the northeast of Mueang Nong Khai District on the shore of the Mekong River, which is marks the northern boundary of the sub-district.
To the west is Hin Ngom Sub-district, to the south Lao Tang Kham of Amphoe Phon Phisai, and to the east the sub-district Ban Duea.
[2] The tambon administrative organization (TAO) as the local government unit was established on 13 February 1997.
[3] The sub-administrative district consists of eight administrative villages (muban).