The exposure of steel to very cold temperatures (cryogenics) as a means to improve properties of the metal has had a controversial history. This study employed several tests to determine differences between D2 tool steel cryo-treated in dry ice (-78°C) versus in liquid nitrogen (-196°C), as compared to control D2 steel (not cryo-treated). These tests showed no major changes between the control and the liquid nitrogen treated steel, but the dry ice (-78°C) treated steel showed narrower XRD peaks, more reproducible hardness measurements, less scatter in the corrosion weight loss, and lower corrosion currents in the cyclic polarization tests in saltwater. All these differences were measured even though there was no measurable difference in retained austenite. The authors hypothesize that the -78°C (dry ice) allowed internal stress reductions, while the -196°C (liquid nitrogen) was too cold to allow any transformations.