The book presents the scientific history of the early days of fuel cells (1838 to 1845). The fuel cell effect was discovered by the Swiss scientist Christian Friedrich Schoenbein. while the English lawyer and scientist William Robert Grove perfected the idea into a working power source. But around 1870 Siemens invented the power generator and electricity was produced by rotating shafts of water wheels, engines and turbines. The book presents for the first time the complete communication between C. F. Schoenbein and R. W. Grove (1838 to 1868). Also, the original analysis based on the physical understanding of 1850 has also been revised and corrected. The updated fuel cell analysis leads to full agreement between theory and experiment. Updated and corrected fuel cell theory Historic review of discovery of fuel cell effect and early development of fuel cell generators Complete correspondence between Schoenbein and Grove from 1838 to 1868 (first publication)