The present invention presents a method for the aerobic production of xanthan by bacteria of the genus Xanthomonas on a solid or semi-solid substrate. In the exemplary embodiment of the method, a substrate is provided that has a total solids content of about 6.5% or higher. The substrate is sterilized and cooled. Bacteria of the genus Xanthomonas are inoculated into the substrate and incubated. After incubation, the bacteria are destroyed, the substrate is either diluted or washed, and the xanthan is isolated.