We have studied theoretically thermal and mechanical properties of nanoporous materials. The thermal conductivity has been estimated with special attention to phonon scattering by nanometer-sized pores. It is shown that the thermal conductivity of a material having several nanometer-sized pores decreases steeply with increasing porosity. The bulk modulus of model nanoporous materials has been calculated using an interatomic potential. It is shown that the bulk modulus of a material having several nanometer-sized pores decreases moderately with increasing porosity. From our theoretical consideration we discuss how we optimize thermal and mechanical properties of nanoporous materials.