We report on the experimental characterization, in the telecom C-band, of group-velocity dispersion (D) in 100-nm high rectangular strip waveguides realized by silicon-on-insulator technology. We compare the experimental results with numerical predictions, showing that 100-nm high waveguides exhibit normal dispersion and that the absolute value of the dispersion coefficient D decreases as the waveguide width is increased. D at 1550 nm varies from -8130 to -3900 ps/(nm·km) by increasing the waveguide width from 500 to 800 nm.