We describe theory and experiments concerning a chemical reaction, the alkaline oxidation of glucose with methylene blue as a catalyst, that is hypothesized to drive fluid motion via an overturning instability, as an example of a "chemoconvective" process. A theoretical model is developed to explain this phenomenon and linear analyses from steady and pseudosteady states are used to predict the basic length and time scales of the patterns which initially appear. These theoretical predictions, using kinetic parameters from recent independent experiments, are contrasted with results from pattern initiation experiments. Preliminary comparisons indicate good qualitative and quantitative agreement. (C) 2001 American Institute of Physics.