Wat Oi is an old temple representing a symbol of Mueang Wiset Chai Chan locating at Mu 10, Tambon Sanchao Rongthong, on the west bank of the Noi River. Follow Highway No. 3454 for approximately 2 kilometers and 1 kilometer from the north of Wat Khian. The temple is assumed to have been constructed in the Ayutthaya period, but there is no evidence by the reign of which king. The ubosot is a huge building consisting of 6 chambers made of brick and plaster in ancient design. The roofs were made of wood and covered with fire-clay tiles, as beautiful as the ubosot of Wat Ratchaburana in Ayutthaya. With Maha-ut design, there is no window in the ubosot.
Special features of the ubosot are the pillars of the gallery in 8 directions. The principal Buddha image, called Luangpho Dam, is made of alloy of brass and tin. Wat Oi was used as a venue to hold the ceremony of taking the oath of allegiance to the king in the Ayutthaya period. In the precincts of Wat Oi, the Children Creation Foundation has provided accommodation for problem children: straying, drug addicted, or illegally behaved. The accommodation is called Ban Dek Klai Wat with the purpose of helping problem children to live better life. They can live with the beauty of natural surroundings and monks help to treat them mentally.