Smart Mobile devices and web services are becoming very popular. Mobile devices are physically constraineddevices; low processor speed, limited memory, limited battery, and slow intermit wireless connection. This implies to take inconsideration these factors when implementing web services for mobile devices. In this paper, we evaluate the RESTful webservice for mobile devices against conventional SOAP web services. The experimental results show that RESTful web servicesoutperform conventional SOAP web services. A recommendation to use RESTful web services on mobile devices has beenconcluded from experimental result.