500 Baht

P#121 belongs to the sixteenth series of Thai banknotes, introduced under Rama IX — Bhumibol Adulyadej — whose reign of over seven decades made him the world's longest-serving head of state at the time of issue. The 500 Baht denomination had by this period become a workhorse note in everyday Thai commerce, and the decision to produce it domestically at the Bank of Thailand Note Printing Works reflected a long-standing policy of printing independence that the central bank had maintained since the facility's establishment in 1969.

The security foil on this series was a meaningful upgrade over earlier sixteenth-series printings, introduced in part as a response to increasingly sophisticated counterfeiting operations detected in Southeast Asia during the early 2010s.