Sillanatham is a neighbourhood in Ottapidaram taluk[1] in Thoothukudi district of Tamil Nadu[2] state in the peninsular India.

Sillanatham is located at an altitude of about 54.05 metres (177.3 ft) with the geographic coordinates of (8°52′29″N 78°04′13″E / 8.8748°N 78.0702°E / 8.8748; 78.0702) in the Thoothukudi district.

The Thoothukudi district is southeast of the Tamil Nadu state.

[4] Sillanatham has an industrial estate of 380 acres owned by SIPCOT (State Industries Promotion Corporation of Tamil Nadu) where the ground breaking ceremony was held on February 25, 2024, for manufacturing electric vehicles and batteries by the Vietnamese electric vehicle manufacturer VinFast and the SIPCOT (joint venture).

[5][6] Sillanatham area falls under the Ottapidaram Assembly constituency.