Thermal stresses due to conjugate oscillatory laminar free convection in an enclosure having thick conducting sidewall have been investigated computationally. Enclosing side wall is considered to have finite conductive properties. Problem has been analyzed using control volume approach and employing ghost nodes at the fluid-solid interface. Outside wall temperatures are assumed to be constant as it is conventionally applicable in many industrial applications. Square cavity is assumed to be filled with a Bousinessq fluid with a Prandtl number of 1.05 containing uniform volumetric sources. Rayleigh number varies from 10(7) to 10(11). The thermal stresses are computed in solid sidewall for various Rayleigh numbers utilizing the plane stress formulation based on the approach of thermo-elasticity. Consequently it was considered that temperature extremely oscillates (strong distractions) with time due to the effect of high Rayleigh number. The thermal stresses develop in the solid wall due to heat transfer and the temperature gradient. The temperature field and the equivalent stress have changed time to time in the solid wall due to oscillatory convection. Finally isotherms, iso-equivalent von Mises stresses, velocity fields are obtained and scrutinised. Therefore the obtained results illustrate a significant change in the buoyant flow parameters and thermal stresses. (c) 2008 Elsevier Ltd. All rights reserved.