We report on ultrafast temperature jump measurements in neat and isotopically mixed ice using two-color infrared spectroscopy. The OH-stretching vibration is applied for rapid heating and for fast and sensitive spectral probing of local thermodynamics conditions. Shock laser heating of bulk ice leads to substantial superheating of the solid phase. The generated superheated state persists over the monitored time interval of 1.3 ns. A limit of superheating (LS) of bulk ice to T-LS = 330 +/- 10 K is observed in HDO:D2O (15 M) and neat H2O samples by ultrafast temperature jumps. Within the stated experimental accuracy an isotope effect could not be recognized for this value. The maximum superheating reduced by increasing the chemical impurities or the initial temperature of the ice sample. (c) 2007 Elsevier B.V. All rights reserved.