The Princess' condition worsened on Tuesday night and she passed away at 2.54 am on Wednesday January 3, 2007.
The Princess had been received treatment for cancer at the hospital for months. Well-wishers had flocked to the hospital since the news spread that she was admitted.
The Princess is the elder sister of two kings of the Chakri Dynasty - King Rama Ananda and the present King Bhumibol Adulyadej.
The royal funeral will take place at the Dusit Mahaprasart Throne inside the Grand Palace. Public who wants to pay respect to the late Princess should head to Sala Saha Thai Samakom inside the grand palace from 1pm to 4pm today.
The mourning period has started from yesterday until the 100th day of her departure, according to the Bureau.
Shortly after the news of her death was announced, people in black dress rushed to the hospital to pay respect to the Princess portrait.
At the time of the announcement, all members of the Royal Family were still on the 16th floor of the hospital a huge crowd was waiting to have an audience with His Majesty the King.
The hospital decorated inside the Chalerm Prakiart Building with black and white clothes to mourn the departure of the Princess.