We have invented a high-performance GPU based volume rendering algorithm on the ubiquitous WebGL platform. As WebGL is emerging as a standard platform for web applications on mobile devices, a remarkable advantage of our approach is that the advanced volume rendering algorithms can run directly on mobile devices such as smart phones and tablets in which GPU is embedded, anywhere and anytime. Technically, we deployed a novel single-pass rendering pipeline, in contrast to the other WebGL volume rendering systems using the multi-pass approach. We extended the pseudo-color shading and ray function blending by using a custom transfer function widget in the web browser, which enables interactive feature enhancement in rendering. And lastly, to get rid of the limitation in the loop iteration for dynamic loops on the current mobile platforms, we devised a WebGL compliant 3D texture slicer as an alternative solution to rendering of large datasets. Extensive experimental results and performance assessments are reported in the paper.