Sidi Mohamed Ould Cheikh Abdallahi (Arabic: سيدي محمد ولد الشيخ عبد الله‎; 1938 – 22 November 2020) was a Mauritanian politician who was President of Mauritania from 2007 to 2008.

He served in the government during the 1970s, and after a long period of absence from politics he won the March 2007 presidential election, taking office on 19 April 2007.

[3][4] Sidi was born in 1938 in the village of Lamden,[5] near Aleg in southern Mauritania whilst a French colony, about 250 kilometers from the capital Nouakchott.

He subsequently studied mathematics, physics, and chemistry in Dakar, Senegal and received a diplôme d'études approfondies in economics in Grenoble, France.

In this speech, he referred to the "dark years" of 1989–1991, condemning the violence of that time, expressing compassion for its victims, and emphasizing the importance of tolerance and reconciliation.

[23] Plans by Sidi's supporters to create a new party to back him were initiated in 2007; the opposition criticized this as potentially meaning a return to a single-party dominant system, as existed under Taya.

[26] Early in the morning of 6 August 2008, Sidi replaced senior army officers; at 9:20 am he was seized from his home by members of the BASEP (Presidential Security Battalion) in a military coup.

[30] The coup leaders announced on 7 August that Sidi's powers had been terminated and that a newly formed High Council of State (including General Mohamed as its president) would govern the nation in a transitional period leading to a new presidential election "as soon as possible".

Mohamed also said that Sidi was being held at the Palace of Congress, was "in good conditions", had not complained, and would be released in a matter of days or weeks.

[33] However, Mohamed was quoted in an interview with Asharq al-Awsat published on 9 August as saying Sidi would not be released for "the time being", citing "security reasons".

[36] Arab League Assistant Secretary-General Ahmed bin Heli said on 11 August, after returning from Mauritania, that he had asked to meet with Sidi but was not allowed to do so.

One of those who met with him said that "his morale was high and he's following the news on the television and the radio" and that he wanted to be allowed to publicly defend his actions as president, as well as meet with supporters.

On 22 January 2009, he attempted to travel to Nouakchott to deliver a speech, but his motorcade was stopped by security forces at Wad Naga, outside of the city.