Thousands of Thais have assembled at Bangkok's royal palace for late-night prayer to mourn King Bhumibol Adulyadej, who died on Thursday.
His body was carried to the palace in a convoy as mourners lined the streets crying. Millions watched live over TV.
Crown Prince Maha Vajiralongkorn has been named as descendant, but has asked for a delay in the procedure. A regent has been nominated.
King Bhumibol was the world's longest-reigning sovereign.
He had been unwell for a long time and died on Thursday. Official grieving will last a year for Thailand.
The cabinet expressed that Friday will be declared a government holiday, and flags are to fly at half-mast for the next 30 days.
With that said people are asked to wear black, and avoid "joyful events" during this period. Cinema screenings, concerts, and sports events have been cancelled or suspended.
News websites have turned their pages black and white. All TV channels in Thailand aired state media programs including live scope of the day's events.
Near-end of the king's life, Prince Vajiralongkorn was moving to the center of civil life. The military has lately sought to polish the image of the prince, a union that may also have bonded the generals' power.
King Bhumibol was beyond help of a long day of attending projects in eastern Thailand in the summer of 1988 when he and Princess Sirindhorn agreed to be conversed by The Times in a Swiss-style chalet by a reservoir built by a donor in honor of the king. The topic turned to the story of "The King and I," which had been forbidden in Thailand as being insolent to the monarchy, and to the West's image of the sparkling life of a king of Siam, corporate in the musical most memorably by Yul Brynner.
"At first, it was all this rubbish about the half-brother of the moon and the sun and master of the tide and all that," King Bhumibol said in his fluent English. He said he found it "irking" to have to live up to legends created by Western writers.
"They wanted to make a fairy tale to amuse people," he said, "to amuse people more than to tell the truth."
In reality, he said, his life revolved around his development projects.
He said he did not care how history would remember him.
"If they want to write about me in a good way," he said, "they should write how I do things that are useful."
