Temperature-programmed reduction (TPR) techniques can yield direct information on the reducibility of catalysts and catalyst precursors and is an excellent technique for characterizing a variety of catalysts. The technique consists of exposing the sample to a flowing mixture of a reducing agent, such as hydrogen, in an inert gas while linearly ramping the temperature. The rate of consumption of the reducing agent is monitored and related to the rate of reduction of the sample. Figure 1 shows the TPR profile obtained for a 10% NiO/Si02 catalyst using a 10% H2/Ar mixture at a flow rate of 30 ml/min and a linear heating rate of 20 K/min. Such a signal gives information concerning the ease of reducibility (temperature at maximum) as well as the extent of reducibility (signal area) of the material being studied. An excellent comprehensive description of this technique is found in the book "TemperatureProgrammed Reduction for Solid Materials Characterization" by A. Jones and B.D. McNicol (Marcel-Dekker, Inc., 1986).