| Time in São Tomé and Príncipe | |
| Time Zone: | Greenwich Mean Time |
| Initials: | GMT |
| Adopted: | 1 January 1912–1 January 2018 1 January 2019 (readopted) |
| Dst: | no |
| Tz: | Africa/Sao Tome |
Time in the island country of São Tomé and Príncipe is given by Greenwich Mean Time (GMT;).[1] São Tomé and Príncipe has never observed daylight saving time.[2]
Under Portuguese rule, São Tomé and Príncipe first observed the local mean time UTC+0:26:56 until 1884, when it adopted UTC-0:36:45. GMT (UTC±00:00) was adopted on 1 January 1912. The country briefly adopted West Africa Time (WAT;) on 1 January 2018,[3] but reverted back on 1 January the following year.[4]
In the IANA time zone database, São Tomé and Príncipe is given one zone in the file zone.tab – Africa/Sao Tome. "ST" refers to the country's ISO 3166-1 alpha-2 country code. Data for São Tomé and Príncipe directly from zone.tab of the IANA time zone database; columns marked with * are the columns from zone.tab itself:[5]