In this paper, we consider the problem of a hot buoyant spherical body with a zero-traction surface ascending through a power-law fluid that has temperature-dependent viscosity. Significant analytical progress is possible for four asymptotic regimes in terms of two dimensionless parameters: the Peclet number, Pe, and a viscosity variation parameter, e. For mild viscosity variations, Levich's classical result for an isoviscous Newtonian fluid is generalized; more severe viscosity variations lead to an involved four-regime asymptotic structure that has similarities with that found for a Newtonian fluid with temperature-dependent viscosity. (C) 2012 Elsevier B.V. All rights reserved.