Thailand began circulating bank notes and coins featuring the image of new King Maha Vajiralongkorn on Friday, officials said.
Thousands queued through the morning in front of the Treasury Department to exchange their old coins with new ones, with notes to be distributed by the banks. 
It is the first time the South-east Asian country has replaced its currency, which previously featured the image of late king Bhumibol Adulyadej, Vajiralongkorn's father, who died 18 months ago. 
Deeply revered as a father figure and moral authority, Bhumibol's death sent the country into a year of mourning. 
The former currency can still be legally accepted until further notice, Thailand's central bank has said.
The new currency was launched on the 236th anniversary of the reigning Chakri Dynasty which is a public holiday in Thailand. 
The anniversary was marked last year with an elaborate ceremony which saw Vajiralongkorn promulgate the new constitution drafted by the ruling military regime.
Political analysts see how the 65-year-old king has used the anniversary as an attempt to strengthen the monarchy's influence.