Computer-based Supervisory Control and Data Acquisition (SCADA) systems have evolved over the past 40 years, from standalone, compartmentalized operations into networked architectures that communicate across large distances. In addition, their implementations have migrated from custom hardware and software to standard hardware and software platforms. 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. These features coupled with low investment cost are especially suited for exchanging information of the SCADA system. This thesis tires to develop an approach for building Web-based SCADA system which is implemented based on the client/server architecture. It also addresses the problems concerning security aspects.The software developed in this thesis tried to route the design of Web-based SCADA system by supporting all the implementation aspects for two case studies; the first one is concerned with controlling water level of a network of dams. This case study discusses and implements the main aspect of the problem from the water level measurement, logging readings to server, getting desired levels of water, controlling the gate of the dam, along with monitoring the logged readings, all with security aspects in mind. The second case study is issued for monitoring the network traffic on a set of Very Small Aperture Terminal (VSAT) modems. The whole project was implemented using open source software and frameworks. Linux was used as the operating system for the server and the clients, PHP was selected as programming language for the server side whereas Perl and C for the client side. MySQL was used as database server. Both of the implemented systems were tested successfully in many different environments, to make sure of its validity and testing its functionality. The environments ranged from Local Area Network (LAN) to Virtual Private Network (VPN).