The study presents a new method to prepare PbS nanocrystals embedded in poly(acrylic acid) (PAA) microstructures by micromoulding in capillaries (MIMIC). The micropattems were fabricated first from aqueous solution of acrylic acid lead monomer, and subsequently solidified by gamma-ray polymerization. The resulting samples were treated with aqueous Na2S solution to convert Pb precursor to PbS in the matrix. The final micropattems of PAA embedded with PbS nanocrystals were of high resolution. The products were characterized by IR, XRD, TEM and SPM, respectively, and the results demonstrated that PbS embedded in PAA was nanocrystals. (C) 2003 Elsevier Ltd. All rights reserved.