The mechanism of reduction of titanium dioxide (rutile) with hydrogen
was studied in the temperature range of 300-500-degrees-C. The process
of reduction was followed by measuring the electrical conductivity of
sintered pellets. The variation of conductivity with the time of redu
ction was divided into three regions: (i) adsorption of hydrogen on th
e defects at shorter times; (ii) autocatalytic reduction of the O2- io
ns on the rutile surface at intermediate times; (iii) outward diffusio
n of oxygen within the rutile pellet at longer times.