ABSTRACT In my thesis work, I have made optical and near-infrared spectroscopic observations of a sample of inclined spiral galaxies, to investigate the influence of dust extinction on the inferred kinematics. These observations have confirmed the previous result reported for edge-on galaxies, that the observed rotation curves of a sample of highly inclined galaxies are highly wavelength dependent, i.e. the velocity gradient in the nuclear region increases towards longer wavelengths. A quantitative model which includes the dust extinction, and takes into account the geometry of the galaxy, and assumes the free-extinction or intrinsic rotation curve, has been developed to explain the observational evidence. The model shows that only the longer wavelengths >0.9 micron provide the intrinsic kinematics of an inclined galaxy, since the line-of-sight geometry of the galaxy implies a large optical depth to the nuclear region. Detailed comparison of the observed rotation curves measured at different wavelengths, and hence optical depth, with the model predictions provides a new and powerful method for determining the distribution and magnitude of extinction in the nuclear region of inclined galaxies. This method is presented as an alternative to that involving photometric colors for determining dust extinction, since it is totally independent of population changes or dust emission. In the majority of the galaxies studied in this work, optical depth of at least 30 have been found along the line-of-sight to the nucleus, which is a much larger value than that obtained using photometric colors. These conclusions suggest that the enclosed mass in the nuclear region of inclined spiral galaxies has previously been underestimated, since a lower velocity gradient has been traditionally inferred from optical wavelengths, e.g., H-alpha. Only measurements at longer wavelengths (infrared or radio) yield the true central mass of an inclined galaxy. Finally, the use of near-infrared wavelength to measure the kinematics of the gas of the obscured nuclear region of inclined galaxies has revealed the presence of regions undergoing strong star formation, which are invisible at optical wavelength. Furthermore, the measurements of the stellar kinematics using near-infrared spectral lines provide a powerful new tool for determining different stellar motions along the line-of-sight in the nuclear region of inclined spiral galaxies.