We have measured the critical currrent density Jc as a function of temperature for a Bi-Sr-Ca-Cu-O sample containing a substantial fraction of a phase with Tc≊110 K and for a Ba2YCu 3O7 sample (TTc≊92 K). The behavior of Jc was deduced from magnetization measurements. For both samples the magnetization at fixed temperature and field decayed logarithmically with time. The values of Jc so derived, allowing for the decay to occur, went to zero for temperatures above 35 K for the Bi-Sr-Ca-Cu-O ceramic and to zero above 70 K for the Ba2YCu3O7 sample. These values are substantially lower than those deduced from dynamic M-H loops.