The growth of the Internet as a massive source of information, and in particular, its use as a new sales channel for consulller products, has led to a situation where Internet consumers suffer from information overloading. They are often faced with an overwhelming. choice of products with very little support to help them make a successful purchase decision. Consumers would benefit from Purchase Decision Support Tools (PDST) to back up their purchase decision making activity. Issues that affect the creation of such tools stem from both the Consumer Buying Behaviour (CBB) domain, and the software development domain. Both these areas have an extensive research background which is covered in the literature survey. Creating commercial software applications such as web based decision support systems is a non trivial task best undertaken by experienced software engineers. However, the current situation regarding availability of software personnel has meant that many applications running today are built by inexperienced developers. In this thesis the author proposes a development method that focuses on providing guidance to less experienced developers in order that they create good quality software. A prototype domain specific decision support tool, to aid the purchase of mobile phones, has been build in line with the proposed development method. The tool has been tested, and the development method evaluated. The thesis concludes that the development method can assist less experienced developers by providing a structured approach, and a wide appreciation of the issues to be addressed. In particular the method provides support with regard to the generation of the rules which underpin the purchase decision support tool.