Mobile devices will become an important platform for Internet access. Due to size constraints, in many circumstances speech is the most desirable mode of input. We have developed a system for spoken query based web navigation and searching. The spoken query is recorded by a lightweight client and transmitted to a server where the computationally intensive continuous speech recognition and query execution are performed. Lightweight clients have been developed that can either be a small downloadable Active X component running within a browser or a small application running on a handheld PocketPC. Through these interfaces, users can search for contents in an Encarta encyclopedia, content of a particular website, or navigate to popular websites. Keywords Mobile devices; Multimodal User Interface; Information Retrieval; Speech Recognition.