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The presence of a finite tangential velocity on a hydrodynamically slipping surface is known toreduce vorticity production in bluff body flows substantially while at the same time enhancing its convectiondownstream and into the wake. Here, we investigate the effect of hydrodynamic slippage on the convectiveheat transfer (scalar transport) from a heated isothermal circular cylinder placed in a uniform cross-flow of anincompressible fluid through analytical and simulation techniques. At low Reynolds (Re1) and high Péclet(Pe1) numbers, our theoretical analysis based on Oseen and thermal boundary layer equations allows foran explicit determination of the dependence of the thermal transport on the non-dimensional slip lengthls.In this case, the surface-averaged Nusselt number,Nutransitions gradually between the asymptotic limits ofNu∼Pe1/3andNu∼Pe1/2forno-slip(ls→0)andshear-free(ls→∞)boundaries,respectively.Boundarylayer analysis also shows that the scalingNu∼Pe1/2holds for a shear-free cylinder surface in the asymptoticlimit ofRe1 so that the corresponding heat transfer rate becomes independent of the fluid viscosity. At finiteRe, results from our two-dimensional simulations confirm the scalingNu∼Pe1/2for a shear-free boundaryover the range 0.1≤Re≤103and 0.1≤Pr≤10. A gradual transition from the lower asymptotic limitcorresponding to a no-slip surface, to the upper limit for a shear-free boundary, withls, is observed in boththe maximum slip velocity and theNu. The local time-averaged Nusselt numberNuθfor a shear-free surfaceexceeds the one for a no-slip surface all along the cylinder boundary except over the downstream portion whereunsteady separation and flow reversal lead to an appreciable rise in the local heat transfer rates, especially athighReandPr. At a Reynolds number of 103, the formation of secondary recirculating eddy pairs results inappearance of additional local maxima inNuθat locations that are in close proximity to the mean secondarystagnationpoints.Asaconsequence,Nuexhibitsanon-monotonicvariationwithlsincreasinginitiallyfromitslowermost value for a no-slip surface and then decreasing before rising gradually toward the upper asymptoticlimit for a shear-free cylinder. A non-monotonic dependence of the spanwise-averagedNuonlsis observedin three dimensions as well with the three-dimensional wake instabilities that appear at sufficiently lowls,strongly influencing the convective thermal transport from the cylinder. The analogy between heat transfer andsingle-component mass transfer implies that our results can directly be applied to determine the dependencyof convective mass transfer of a single solute on hydrodynamic slip length in similar configurations through straight forward replacement of Nu and Prwith Sherwood and Schmidt numbers, respectively.