An analytic solution for the normalized intensity for powder x‐ray diffraction has been obtained for a simple two‐dimensional lattice using a linear approximation for the interference function. The analytic solution, where the Bragg peaks are strongly asymmetric, is compared to computer simulations using the Debye formula, and is shown to be in closer agreement than earlier numerical solutions by Warren and others. For a two‐dimensional structure consisting of more than one monolayer of atoms, the shape of the Bragg peaks is modulated by the structure factor. This structure factor modulation provides a continuous plot of the structure factor over the range of the diffraction tail and thus provides valuable information about the structure of the layer. It is demonstrated that because of structure factor modulation the Warren expression which relates the width of Bragg peaks to layer size cannot be used for a two‐dimensional sheet with more than one layer of atoms, and it is proposed in such cases that measuring the low‐angle side width of half‐maximum intensity can be used for determination of the layer size. Single molecular layer MoS2and WS2suspensions, prepared by exfoliation, provide excellent randomly oriented two‐dimensional systems for demonstrating the unique features of powder x‐ray diffraction patterns of two‐dimensional materials and for structure identification using Bragg peak profiles. ©1996 American Institute of Physics.