"It's a fine thing to have ability, but the ability to discover ability in others is the true test" (Elbert Hubbard) As we approach the new millennium, the advances in information and communication technology overloads our senses with massive amount of information which must be categorized and presented efficiently for better understanding of the topic or even to generate a response. Efficiency and performance are directly related to mental capacity. Although, many efforts to measure mental capacity adequately are still in progress, there has been numerous previous attempts to evaluate and compare human mental capacity and performance. This study addresses this last and the most daunting frontiers of human mechanism and introduces a technique to evaluate mental capacity of human subjects under different physiological and environmental conditions. The mental capacity battery has been developed to measure the mental capacity by comparing Response Time (RT), Accuracy (AC) and Repeatability (RP) of a subject, testing under normal as well as stressed conditions. One can, hence, evaluate the stress and the environment that affects human mental capacity.