Thailand bade a final goodbye to its beloved late King Bhumibol Adulyadej on Thursday in a ceremony steeped in ancient rituals, processions and Buddhist rites that drew hundreds of thousands of mourners.

The ashes and bones of Thailand's King Bhumibol Adulyadej were returned to the palace on Friday as part of an elaborate, five-day cremation ceremony that drew hundreds of thousands of black-clad mourners to Bangkok's historic old quarter.

The $90 million funeral marks the end of an era for many Thais who had only ever known King Bhumibol as their monarch.

It ushers in the reign of the late king's son King Maha Vajiralongkorn, or Rama X, who ascended the throne last year but whose coronation can only take place after his father's funeral.

Many mourners stayed to watch as smoke rose from the crematorium. Some broke down in tears.

King Vajiralongkorn has overseen sweeping changes to the royal household, including the running of palace finances.

Earlier in the day members of the Thai royal family, visited dignitaries and government officials and placed sandalwood flowers at the royal funeral pyre.

The ceremony on Thursday brought Thailand to a standstill as many businesses, including banks, shut to honour the late king.