St. Mary's Seminary Senior High School (SMASCO) formerly is a reputed second cycle institution for boys located in Lolobi Kumasi in the Oti region of Ghana which was part of the Volta region until December 2018 when it was carved out.

SMASCO as it is popularly called, was initially founded as a minor seminary on the 29th day of  September 1961 by the Roman Catholic Church under the leadership of His Lordship Most Reverend Anthony Konings a Dutch missionary priest who was then the Bishop of Keta Diocese. The institution was intended to serve both as the minor seminary for the entire Keta Diocese and as a secondary school for the area. St. Mary's Seminary Secondary School opened admission to non-seminarians and students of all denominations right from the very beginning of its foundation.

The school was absorbed by the government of Ghana in 1977 and it became government-assisted instituion. SMASCO has become one of the most popular and one of the best performing second cycle institution in the Volta and Oti Regions og Ghana. The school's motto “Domine Adsum” meaning ‘Lord I am present’.

Since its inception, SMASCO has been headed by Catholic Priests and many of its teachers till date are Catholic Priests with the Rev. Fr. William Van Frankenhausen, SMA as the frist headmaster.

The students are called SMASCANS and the alumni are nicknamed CARDINALS under the recognized alumni body SMASCO Old Boys Association (SMOBA) composed of members of the various year groups of completions.