Cold denaturation is a general property of globular proteins, but it is difficult to directly characterize since the transition temperature of protein cold denaturation, Tc, is often below the freezing point of water. As a result, studies of protein cold denaturation are often facilitated by addition of denaturants, or by using destabilizing pHs, or extremes of pressure, or by reverse micelle encapsulation, and there are few studies of cold induced unfolding under near native conditions. The thermal and denaturant induced unfolding of single domain proteins is usually cooperative, but the cooperativity of cold denaturation is controversial. The issue is of both fundamental and practical importance since cold unfolding may reveal information about otherwise inaccessible partially unfolded states and because many therapeutic proteins need to be stabilized against cold unfolding. It is thus desirable to obtain more information about the process under non-perturbing conditions. The ability to access cold denaturation in native buffer is also very useful for characterizing protein thermodynamics, especially when other methods are not applicable. In this work, we study a point mutant of the C-terminal domain of the ribosomal protein L9 (CTL9) which has a Tc above 0 C. The mutant was designed to enable the study of cold denaturation under near native conditions. The cold denaturation process of I98A CTL9 was characterized by NMR, CD, and FTIR. The results are consistent with apparently cooperative, two-state cold unfolding. SAXS studies show that the unfolded state expands as the temperature is lowered.