Computer-based Supervisory Control and Data Acquisition (SCADA) systems have evolved over the past 40 years, from standalone, compart operations into networked architectures that communicate across large distances. On the other hand, the World Wide Web (WWW) has become a convenient way to access information on the net because the Web browser integrates different network services into a common easily accessible user interface. This thesis tries to develop an approach for building Web-based SCADA system which is implemented based on the three tier client/server architecture. The software developed in this thesis tried to route the design of Web-based SCADA system by supporting the implementation aspects for a chosen case study; concerned with monitoring and controlling an electric power station. This case study discusses and implements the main aspects of the problem which is the power station measurement, logging readings to server, getting desired ranges for each parameter; send controlling commands, and monitoring the measured readings. The Implemented system was tested successfully in many different environments, to make sure of its validity and testing its functionality. The environments were Local Area Network (LAN) to global internet network. The PHP 5.0.1 server side scripting language was used to develop the website, apache web server 2.5.1 was installed on the system server as a local web server, and the MySQL Server 4.0.20.is adopted as the database system, Visual Basic 6.0 was also used to complete the system functions.