The hearing will be held against a backdrop of allegations that prisoners in the restive South have been tortured, and drug suspects and migrant labourers abused.
As one of the 155 states party to the Convention against Torture and other Cruel, Inhuman or Degrading Treatment or Punishment, Thailand must undergo examinations before the Committee of 10 independent experts on Wednesday and Thursday.
The UN Committee Against Torture will hold talks with a government delegation and also hear from NGOs in public sessions that will be webcast live by the Office of the High Commissioner on Human Rights (OHCHR) in Bangkok.
In a report to the committee, Amnesty International said incidents of torture and ill-treatment of prisoners in military and police custody, and the Thai prison system, are well-known.
Methods commonly used during interrogations to extract confessions include beatings, electric shocks, being stripped naked, exposure to extreme temperatures and asphyxiation.
The National Human Rights Commission (NHRC) said that between 2007-2013 it received 134 complaints of torture, including 14 in 2013. Just over 75% of all complaints came from the southern provinces, of which 71% concerned alleged torture by the army.
For that same period, the Muslim Attorney Centre received 382 complaints of torture, including 57 in 2013. Migrant labourers and drug suspects also faced ill-treatment, as did red-shirt protesters during enforcement of the emergency decree in Bangkok in May-June 2010, rights groups alleged.
Yu Kanosue, OHCHR regional representative for Southeast Asia, said Thailand must incorporate torture as a crime in domestic law, as other countries had agreed to do.
Currently, the prosecution of suspected perpetrators of torture could be done under other crimes defined in the Criminal Code such as murder, attempted murder, grievous bodily harm and battery.
The government submitted its report to Geneva in February 2013. The NHRC and six other reports by NGOs will also be considered by the UN committee.
Amnesty International said the lack of accountability for torture in Thailand stems from legal provisions providing impunity from prosecution in the 1914 Martial Law Act and the 2005 emergency decree, and for acts of intimidation against individuals seeking redress.