Inhibitors of kinase activities can be mechanistically diverse, genomically selective, and pathway sensitive. This potential has made these biological targets the focus of a number of drug discovery and development programs in the pharmaceutical industry. To this end, the high-throughput screening of kinase targets against diverse chemical libraries or focused compound collections is at the forefront of the drug discovery process. Thus, the platform technology used to screen such libraries must be flexible and produce reliable and comparable data. The Caliper HTS microfluidic platform provides a direct determination of a peptidic substrate and phosphorylated product through the electrophoretic separation of the two species. The resulting data are reliable and comparable among screens and cover a broad range of biological targets, provided there is a definable peptide substrate that permits separation. Here we present a method for the high-throughput screening of the cyclic AMP-dependent protein kinase (PKA) as an example of the simplicity of this microfluidic platform.