Web Applications have become a critical component of the global information infrastructure, and it is important that they be validated to ensure their reliability. Exploiting user session data is a promising approach to testing Web applications. However, the effectiveness of user session testing technique depends on the set of collected user session data: The wider this set, the greater the capability of the approach to detect failures, but the wider the user session data set, the greater the cost of collecting, analyzing and storing data. In this paper, a technique for reducing a set of user sessions to an equivalent smaller one is implemented. This technique allows reducing of a wider set of user sessions to an equivalent reduced user session and pages, sufficient to test a Web application effectively. Reduction of a user session for several web applications like TCENet Web application, Portal application, Social Networking, Online shopping, Online Library is carried out in order to validate the proposed technique; and our technique is compared with HGS, Random Reduction technique and the Concept Lattice technique to evaluate its efficiency.