Sadao (Thai: สะเดา, pronounced [sā.dāw]) (Malay: Sendawa) is district (amphoe) on the border of Malaysia in Songkhla province, southern Thailand. The capital of the district is also called Sadao town. The small town of Danok (Thai: ด่านนอก, RTGS: dan nok), 13 km south of Sadao town in tambon Samnak Kham is the major border crossing between Thailand and Malaysia. The immigration, customs, quarantine and security checkpoint on the Malaysian side is called the Bukit Kayu Hitam ICQS checkpoint. A second smaller border crossing is in the district at Padang Besar, 12 km west of Sadao town.