Effect of a magnetic field on the gel growth of PbBr2 was studied by observing nanocrystallites in silica gel. The control of the reaction between the Pb(NO3)(2) and K-Br solutions by the diffusion process in a sodium metasilicate gel was used for the growth of PbBr2 crystals. The nanocrystallites formed in the gel prepared with and without the magnetic field have been examined by transmission electron microscopy. The following results were obtained. (1) Oriented PbBr2 nanocrystallites were obtained in the gel prepared with magnetic field. (2) The size of these nanocrystallites was four times larger than that of crystallites grown in the gel prepared without magnetic field (25 nm). (c) 2005 Elsevier B.V. All rights reserved.