Magnetic measurements have been used to evaluate the critical current densi
ty J(c) for YBa2Cu3Ox samples with various oxygen content (x) and, for part
ially oxygenated samples (x similar to 6.5), with different degrees of oxyg
en disorder. The current density has been expressed in terms (T/T-c)(-delta
), where delta decreases linearly with x for x < 6.6 and becomes constant f
or 6.6 < x < 7. Moreover, the variation in T-c with oxygen content has been
used to represent J(c) as J(c) = J(o) (x/T-c)(-n), where J(o) is almost co
nstant and n is temperature dependent. At a given temperature ratio (T/T-c)
, the oxygen disorder enhances the critical current density and weakens its
field dependence. It is argued that the increased number of Cu(1) + 3O clu
sters with increasing disorder may cause additional pinning centres and aff
ect the J(c) behaviour.