A new independent method for reconstructing tomographic images of the ionosphere is described. The mathematical approach makes use of an interior-point algorithm for solving quadratic programing problems. The procedure has been designed to be fully automated and to work in either two or three dimensions. Results are presented using experimental data obtained during a campaign carried out in Scandinavia in November 1995 for which independent verification from the European incoherent scatter (EISCAT) radar and the Kiruna ionosonde are available. A comparison is made between the mean diurnal variation of maximum electron density obtained from the tomographic reconstructions and the parameterized ionospheric model. ¿ 1998 American Geophysical Union