Single polyelectrolyte component microcapsules and multilayers exemplified by poly(allylamine hydrochloride) (PAH), have been prepared using a method of glutaraldehyde (GA)-mediated covalent layer-by-layer (LbL) assembly. The GA cross-linking of the adsorbed PAH results in surfaces covered by reactive aldehyde groups which can then react with PAH to result in another layer of covalently liked PAH. The repeated assembly of single polyelectrolyte in an LbL manner can be thus achieved. The PAH multilayers can grow linearly along with the layer number, and their thickness can be controlled at the nanometer scale, as verified by UV-vis abortion spectrometry and ellipsometry. Single polyectrolyte microcapsules are obtained after removal of the template cores at low pH. The morphology and integrity are confirmed by scanning force microscopy and confocal laser scanning microscopy.