Abstract. This paper presents a development and an evaluation of a mobile mashup generator system to compose mobile mashup applications and Tethered Web services on a mobile device (TeWS). With less programming efforts, our system and description language framework enables a rapid development, a reusability of working components and a delivery of new cooperative mobile mashup applications. Working components in the mashup execution are derived from a combination of existent mobile applications, JavaScript automated Web page data extractions, and RESTful Web service consumptions. The state of art generator system is evaluated with novice and expert composer groups, to validate the usability of the system and the expressibility of our Mobile Application Interface Description Language (MAIDL). Complex mashup examples are provided to demonstrate new cooperative applications of generated Web services, which enable platform-independent functionality exchange across devices via tethered HTTP communications.