Maintenance is essential for global companies to maximize their manufacturing productivity and customer satisfaction so that their products or services can be reached out to every corner of the world. Hence, these companies have been searching for an efficiency maintenance that can provide just-in-time maintenance remedy action or instantaneous response to service requests. Conventional types of condition based monitoring are installed locally in a plant or a factory. They usually require lots of instruments and redundancy, heavy manpower, including local experts who are expensive to keep, difficult to move around, and lack of future expandability. Online monitoring (or so called Web-based monitoring) is one of the most efficient methods to optimize conventional machine monitoring. The use of Web-based monitoring not only reduces the cost of having numerous instruments and redundancy of equipment onsite, but also allows remotely located experts to help monitoring without the need to have them locally. In view of the significant benefits provided by the Web-based monitoring, in this thesis, a novel Web-based monitoring system has been developed and reported here. It includes 1) a Web-based machine fault diagnostic system, 2) a modified architecture for increasing efficiencies in processing and communication, and 3) several security mechanisms to ensure the security of the Web-based monitoring system. The Web-based machine fault diagnostic system can provide remote and online machine operational data acquisition and health monitoring. Its design uses a number of Web-enabled virtual instruments and multi-media tools to monitor the inspected machine. Through the Internet, sensory information and operating conditions of the machine can be transferred from a factory to a distantly located office. Hence, the maintenance staff or experts can evaluate the health conditions of the machine remotely and if required, provide instantaneous remedy advice. To shorten the response time on the Internet and avoid heavily loading the main server, the architecture of the Web-based system has been re-designed. The modified system will have different communication routes to ease the load of the main server. It also uses less communication time and computational resources. To further shorten the response time, the programs written for the Web-enabled virtual instruments have been modified. In the original system, all virtual instruments working for machine fault diagnosis were bundled into one program for ease of transmission via the Internet. However, the time required for processing and transmission was tremendous. In the new system, all virtual instruments have been written as modularized programs. Each virtual instrument is a single-tasked program. The remote user only downloads the program(s) that he wants. Hence, the time for transmission and processing has been significantly reduced. To ensure confidentiality during the communication of company’s machine information on the Internet, several security mechanisms have been built into the system. Encryption technology is added to prohibit unauthorized data usage. Message digest is used to avert unauthorized data alteration. Digital signature is employed to verify the data has been sent by the authorized parties. Besides, restricting the access privilege and the usability of the program according to the priority of authorized users has been used to prevent illegal usage of both the data and programs. These, coupled with the use of password protection ensure that the data security of the system has been significantly enhanced. Equipped with the Web-based monitoring system, authorized browsers can monitor any machine anywhere and at any time. Instantaneous decision can be made by experts located remotely to suggest remedy actions or alter the production plan in case a particular machine unexpectedly malfunctions. Hence, our system works more effectively and safely as compared to those conventional Web-based monitoring systems.