According to Bro. Ken Thompson who taught English for 15 years at Mang’u High School, "mang’u" is a Maasai word meaning "that’s not me you smell." Bro. Ken said: "When the Maasai hunted lions in the tall grass, they would shout "mang’u, mang’u" to inform their fellow hunters of the situation!"The school is also known as "’Dayton’" (although very few students are actually aware of this) because of the school’s association with University of Dayton, a Catholic university founded by the Society of Mary (the Marianists) in 1850 in Dayton, Ohio, United States.
Mang’u High School is a school that has made tremendous contribution to Kenya’s history. The school boasts of a high profile of many successful alumni among them politicians, lawyers, businessmen, clergymen, scientists, engineers, doctors and pilots. Among the high profile politicians who studied at Mang’u High School are President Mwai Kibaki who attained the maximum possible score, former Vice-President Moody Awori, Cabinet ministers George Saitoti who was also a former vice president, John Michuki who also met President Mwai Kibaki at Mang’u and is a former school captain. Other cabinet ministers are Dr Mukhisa Kituyi, Kipruto Arap Kirwa, Cyrus Jirongo and the late Tom Mboya who was one of Kenya’s principal leaders that agitated for independence plus other members of parliament. Other notable alumni include Cardinal Maurice Michael Otunga, Archbishop Ndingi Mwana Nzeki, Archbishop John Njenga who also met Mwai Kibaki and Moody Awori at Mang’u and says he taught Hon. Awori catechism. Others are Bishop Antony Muheria, Josphat Konzolo former director NSSF (National Social Security Fund) and Dr. Joshua Noreh who performed Kenya’s first Invitro-fertilization.In recent times the school has continued to produce great achievers, some of whom have been ranked in the top ten nationally in the KCSE exams. Past students have been admitted into top schools in the US, UK and Australia including Yale and Harvard.
The first phase of construction was completed in 1972 and all the 253 students moved in. After that, very little has been done to complete the second phase and of course nothing for the third phase, yet the student population is already in the third phase.The school has got a swimming pool,fields which are to stardards,buses which enable transport to be efficient enough, a mordern library,a block of labolatories including aviation laboratory,a chapel , staff quaters,a mordern staffroom and other facilities.