Cloud computing is one of the major emerging technologies of the early 21st century, and has the potential to boost socio-economic development significantly. While cloud computing has traditionally meant software technology, of late there has been active research on cyber-physical cloud systems involving vehicles and mobile robots. In this paper, a set of mobile field robots linked by wireless communication is connected to a cloud server for the purpose of environmental monitoring. One of the robots is used as a base station, while the others are equipped with air quality sensors and on-board microcontrollers for navigation and control. The air quality data are transmitted to the base station robot, which forwards them to the cloud-based server for storage, retrieval, and visualization. The cloud server can also be used to perform computation-intensive functions like image processing using the Google Recognition Engine. A prototype system consisting of three networked mobile robots with open source microcontrollers and air quality sensors connected to a cloud server is developed, and experimental results are presented to illustrate the effectiveness of the proposed method. © 2014 IEEE.