High temperature compliance testing in four-point bending geometry were performed at various temperatures in air to understand visco-elastic behaviour of SiC ceramics sintered with R2O3-AIN (R= Y, Lu) and YAG-AlN additives. The stiffness, calculated from the slope of the loading-unloading curve, essentially characterises the elastic and fast recoverable anelastic components of the material's behaviour. The slow anelastic and plastic behaviour can be determined from the loop area. Excellent visco-elastic behaviour were observed for SiC sintered with Lu2O3-AlN additives as compared to that of with Y2O3-AlN or commercial SiC(Eka-SiCT). Substitution of Y3+ by Lu3+ modifies the grain boundary composition and thickness which governs the high temperature mechanical behaviour. HRTEM investigation on grain-boundary elucidate the property-microstructure correlation. (c) 2008 Elsevier B.V. All rights reserved.