The oxygen content in YBa2Cu3O7-delta has been varied by substitution
at Ba site with Sr or K and its influence on the structural and superc
onducting properties has been studied. These properties are compared w
ith that of unsubstituted YBa2Cu3O7-delta prepared by quenching. The i
ncrease in delta value of YBa2Cu3O7-delta decreases the T(c) drastical
ly, whereas in YBa2-xKxCu3O7-delta system increase in the delta value
(as high as 0-92) does not affect the superconducting transition tempe
rature, which remains above 77 K. In the YBa2-xSrxCu3O7-delta system,
as Sr content increases there is marginal decrease in the oxygen conte
nt as well as in the superconducting transition temperature.