<p>Rapid and easy detection of toxic chemical warfare agents is essential for public safety, and one possible approach is to utilize photoelectrochemical sensors for the detection of chemical warfare agents. Here, a portable photoelectrochemical system, including a mechanical structure, hardware circuitry, and software system, is designed to measure the concentration of chemical warfare agents by detecting the photocurrent generated by the photoelectrochemical reaction of specific nanocomposites with chemical warfare agents. The system’s rapidity, sensitivity, and accuracy were demonstrated by building an experimental prototype for experimental validation, contributing to further chemical warfare agent detection.</p>