We propose SWS and LWS spectroscopy of selected lines in cD galaxies with cooling flows to determine the amount and physical conditions of cool (300-1000 K) atomic/molecular gas. Ground based observations of near IR H2 and [FeII] lines show that these are the galaxies with the largest column densities of warm gas (2000-7000 K) compared to bolometric luminosity and stellar mass. The ratio L(H2)/Lbol is 1-2 orders of magnitudes larger than Seyferts and a factor >4 larger than in the most extreme starbursters. Several arguments suggest that these galaxies should have considerably larger column densities of cool (300-1000 K) gas, so they should be bright, and have the largest equivalent widths of all galaxies, in the major coolants of this phase: [OI], [CII], [SI], [FeI], [FeII] and H2 0-0 lines. From these observations we will estimate the physical conditions (column density, temperature) of the cool gas component and compare the results with model predictions for molecular clouds excited by shocks, X-rays, and thermal conduction. The unusually large column densities of warm H2 may be related to the large amount of thermal energy in the hot gas, which can be tapped through its X-ray emission or thermal conduction. These observations also offer a direct test of cooling flow models, which postulate large reservoirs of cool gas in cooling flow clusters. It should be noted also that, in contrast to starbursters and Seyferts, cD galaxies are little represented in the GT proposals. Our observations will therefore guarantee that these potentially bright extragalactic line emitters are not overlooked by ISO spectrometers.