5 Sen - Hassanal Bolkiah 1st portrait

Brunei's first decimal coinage series launched in 1967–68 as the nation prepared to sever its currency union with Malaysia and Singapore. The three countries had shared the interchangeable Malaya and British Borneo dollar since independence, but the currency agreement broke down in 1967 when Singapore and Malaysia struck their own separate issues, effectively forcing Brunei to establish its own coinage identity under Sultan Hassanal Bolkiah, who had ascended the throne just months earlier following his father's abdication in October 1967.

Production ran through 1977 before the portrait was updated — a relatively short series life that keeps earlier dates modestly scarcer in uncirculated condition.