Powell pointed out, in 1950, that it is impossible to make reliable predictions as to which substances will form a clathrate structure . This is no longer true. Crystal structure prediction in combination with grand canonical Monte Carlo simulations is a powerful method for the prediction of clathrate structures and their properties. Using such methods and a highly accurate multipole-based force field, we have predicted novel clathrates of resorcinol, oand mfluorophenol and TTBI that adsorb CO 2 , CH 4 and Xe. We have found 84 structures that are mechanically stable both when empty and fully saturated with guest molecules. We have calculated the equilibrium adsorption of Xe, CH 4 and CO 2 , at several temperature and pressures, finding that Xe is in general most strongly adsorbed, and CH 4 quite weakly.