In this study, new de nitions of the Gray weight and the Gray map for linear codes over R = Z25 + uZ25; where u2 = u are de ned. Some results on self-dual codes over R are investigated. Furthermore, the structural properties of quadratic residue codes are also considered. Also two self-dual codes with parameters [22; 11; 6]; [24; 12; 8] over Z25 are obtained.
