Software products can be categorized into three types namely bespoke, market driven and customizable generic products. Each of these products is facing different problems in their development and to address these problems different software process models have been introduced. The use and validation of different software process models for bespoke and market driven products have been discussed in earlier work. On the other hand, less attention was paid to the customizable generic products. Our thesis will fill this gap by conducting a case study on evolutionary prototyping (EP) for customizable generic products. The main aim of the thesis is to make an initial validation of EP for customizable generic products. In order to fulfill the aforementioned aim we performed a literature study on prototyping and EP, together with development of two customizable generic products. During this development process, we used approach of EP. The results from our investigation will provide researchers and practitioners with a deep insight to the EP and also to guide them in making decision regarding the use of EP. The main findings from our investigation are as follows: • EP is not used standalone as a software process model. Rather it is used as a concept that can be augmented with some iterative software process model. • Negative and positive aspects of EP were highlighted by discussing situations where it could be a better choice, with its advantages and disadvantages. • An initial validation was performed on EP for customizable generic products. Reported results from this case study show that the selected approach is a good choice when you want to have innovative product, clear ambiguous and sketchy requirements, discover new requirements, save resources of software testing, involve and satisfy customer. EP shows vulnerabilities in documentation of product and quality of code.