A model for the dissolution of a bubble in blood is presented in this paper. The gas inside the bubble is oxygen and the collapse of the bubble is controlled by the diffusion of the gas from the bubble surface into the surrounding blood. The diffusion is facilitated by the oxygen uptake reaction between the dissolved gas and the hemoglobin, which is described using the Hill saturation curve. The model consists of a system of coupled differential equations describing the related mass transfer physics in an expanding computational domain, which follows the moving interface between the shrinking bubble and the surrounding blood. The main findings regarding the important collapse time of microbubbles in blood indicate that this time may vary from 10 s to 2 or 3 h depending on the size of the bubbles and on the parameters which specify the blood conditions. (C) 2009 Elsevier Ltd. All rights reserved.