The hearings to be broadcast live on national radio and television were organised by a state body empowered to look into widespread abuses committed over a period of 43 years, from independence from France in 1956 to 1999.
The Equity and Reconciliation Commission (IER) was tasked with investigating and documenting "grave" human rights abuses, notably during the 1960s and 1970s, a period under the rule of the late King Hasan II known in Morocco as "the years of lead".
However, to avoid reviving old tensions, there will be no naming of names as participants are not allowed to identify individuals responsible for the violations.
Some of the torturers are believed to still hold high positions in the state apparatus, particularly the military.
The IER says it has received 22,000 files. About 200 people - victims, relatives and witnesses - were given an opportunity for 20 minutes each to present testimony and tell their tales of arbitrary detentions, disappearances or torture at the hands of security agents.
The hearings, to start on Tuesday evening in the capital Rabat, are scheduled to take place in 10 different cities across the kingdom over a period of 10 weeks.
"It's almost unheard of in this part of the world for victims to be given an official platform to relate their experiences of abuse"
Hanni Megally, International Centre for Transitional Justice
"The impact of these hearings ... will be enormous, not only in the country but throughout the region," said Hanni Megally, director for the Middle East and North Africa at the US-based International Centre for Transitional Justice.
"It's almost unheard of in this part of the world for victims to be given an official platform to relate their experiences of abuse," he said.
The IER, led by respected former political prisoner Driss Benzekri, is expected to present a final report in April that will set out the reasons and institutional responsibilities for grave violations up to 1999.
Most victims have asked for reparations, mainly in the form of financial compensation.
But the commission's statute was a disappointment for many human rights activists in Morocco who had lobbied for punishment of those responsible for torturing or killing political dissidents.
"This is a good initiative but conditions of transparency must be met at these hearings," said Abd Allah bin Abd al-Salam, a member of Morocco's main independent human rights group AMDH.
King Muhammad VI is more
reform-minded than his father
"Witnesses ... must be allowed to give names of people responsible for past human rights violations. One can't talk about truth if these torturers still occupy cushy jobs in the state and in its institutions," he said.
Long considered the most Western-oriented country in the Arab world, Morocco was ruled for 38 years until his death in 1999 by a monarch who relied on a ruthless security apparatus.
King Hasan, human rights groups and historians say, imprisoned thousands of perceived opponents, leftists, Islamists as well as real and imagined coup plotters.
Soon after ascending the throne, his son, now 41, created a board that financially compensated 4000 victims of past abuses.