Information Transfer across Chu Spaces Johan van Benthem Abstract: Chu spaces are a new model for information structure (cf. J. Barwise & J. Seligman, "Information Flow", Cambridge UP, 1997) and for mathematical structure in general (cf. Vaughan Pratt's ongoing work at the homepage http://boole.stanford.edu/live). Their properties are usually developed as a form of category theory. In this note, we show how they may also be viewed as models for a two-sorted first-order language, and we determine the exact flow of information across the natural Chu transforms. Our analysis is akin to that of process graphs via bisimulation and modal formulas.