When oppositely-charged polymers are mixed in water they self-assemble into polyelectrolyte complexes (PECs). These complexes have numerous technological applications that require control over their shape. To this end, we show how PEC geometry can be tailored through photodirected assembly. A commonly-used weak polycation, poly(allylamine) (PAH), was co-dissolved in a basic solution (significantly above its effective pKa) with a commonly-used polyanion, poly(styrene sulfonate) (PSS), and a photoacid generator (diphenyliodonium nitrate). The solution was then irradiated with UV light through photomasks to spatially control the protonation (and therefore the ionization) of PAH. The ionization resulted in the formation of insoluble PECs, whose shapes were predictably tuned by varying the photoirradiation pattern. Also analyzed were the phase behavior of PAH/PSS/diphenyliodonium nitrate mixtures, and the kinetics and spatial resolution limits of their photodirected assembly. This revealed that pH-mediated photodirected assembly works well for macroscopic structures (i.e., larger than about a millimeter in size), but is impeded by ion diffusion when smaller irradiation sites are used. (C) 2015 Elsevier Ltd. All rights reserved.