We have undertaken an experimental investigation to determine the transient current characteristics of membrane-covered Clark-type microdisc electrode oxygen sensors and have compared the results with those obtained using the two-dimensional numerical simulation methods described previously (D.J. Gavaghan, J.S. Rollett and C.E.W. Hahn, J. Electroanal. Chem., 325 (1992) 23), We obtain improved agreement between experiment and theory, and, in particular, are able to verify the non-Cottrellian behaviour of the switch-on transient for membrane-covered microdisc electrodes that we had previously predicted.