In this thesis, complementary-dual (LCD) quasi-twisted (QT) codes over a finite field are studied. Sufficient conditions for certain classes of these codes to be LCD are provided. Issues related to the decomposition and construction of ome classes of imple-root and repeated-root QT codes over finite commutative chain rings are considered. Finally, a generator matrix for some classes of quasi-cyclic (QC) codes over a finite chain ring is provided.