Structures of TiO2(1 1 0) surfaces between p(1 x 1) and p(1 x 2) are observed by scanning tunneling microscopy (STM). We confirm existence of two types of p(1 x 2) rows by comparison with results of impact collision ion scattering spectroscopy (ICISS), i.e., one has Ti2O unit rows on low reduced surface, and another has Ti2O3 unit rows on the heavily reduced surface. We also found that: (1) the low energy electron diffraction (LEED) on the Ti2O surface shows the p(1 x 2) pattern though the every two spots for [(1) over bar 1 0]-direction is intense, and (2) the reflection high-energy electron diffraction (RHEED) on the Ti2O surface shows the only p(1 x 1) pattern though the surface manifestly has p(1 x 2) periodicity. The growing process of p(1 x 2) surface with Ti2O unit rows from the p(1 x 1) surface is also elucidated. (C) 2002 Elsevier Science B.V. All rights reserved.