Levine [5] introduced the concept of Generalized closed sets in topological spaces. Also the notion of semi-open sets in topological spaces was initiated by the same Levine [4]. Bhattacharyya and Lahiri [1] introduced a class of sets called semi generalized closed sets by means of semi - open sets of Levine[4] and obtain edvarious topological properties corresponding to [5]. Sundaram et al. [12] introduced and studied the concept of a class of maps namely g-continuous maps which included the continuous maps and a class of gc-irresolute maps. In this thesis, we generalize the concept of semi-generalised closed sets to (1,2) semi-generalised closed sets and obtain various bitopological properties. The generalizations, in most of the cases, are substantiated by suitable examples.