The present thesis embodies the researches carried out at the Aligarh Muslim University, Aligarh. The thesis has been divided into seven chapters. Besides the introductory first chapter, the second chapter deals with Jacobi type and Gegenbauer type generalization of certain polynomials, third and fourth chapters concern with $q$-analogues of the Jacobi type and Gegenbauer type generalized polynomials and certain classical polynomials respectively. The last three chapters i.e. fifth, sixth and seventh deal with the generalization of the exponential operators obtained by Dattoli and his collaborators. Each chapter is divided into a number of sections. Definitions and equations have been numbered chapter wise. The section number is followed by number of equation e.g. (4.3.2) refers to equation number 2 of section 3 of chapter 4.