Thousands of Moroccans are expected to join nationwide protests to demand that King Mohammed hand some of his powers to a newly elected government and make the justice system more independent.
The street protests have been initiated by a group called "The February 20 Movement for Change" which has attracted 19,000 Facebook fans since the Egyptian and Tunisian revolts.
The government has worked since the king's enthronement in 1999 to repair, with mixed success, a bleak legacy of human right abuses, widespread poverty and illiteracy left after the 38-year rule of his father King Hassan.
The revolutions, especially in neighbour Tunisia, have brought the issue of constitutional reform back onto the agenda after a crackdown that followed suicide bombings in 2003 and the rapid rise of a political party led by a former security official close to the king.
Morocco is officially a constitutional monarchy with an elected parliament.
But the constitution empowers the king to dissolve the legislature, impose a state of emergency and have a key say in government appointments including the prime minister.