The content of this book is Thermal convection problems in fluid and porous medium and some results on double diffusive convection, porous media, Couple stress fluid, rotation and sore effects. This book contains six chapters with the first on Introduction and basic equations. In second chapter, we discuss the onset of double-diffusive convection in a couple-stress fluid-saturated horizontal porous layer is studied using linear and weak nonlinear stability analyses. Later chapters give the applications of different parameters.