computational problems is a central issue in environments of Grid computing. Two important scenarios arise from this issue. First, as the amount of installed applications increases, the difficulty of finding an explicitly desired application for reuse also grows. Simultaneously, the possibilities of suitable replacement of software pieces in response to user requirements increase too. Second, an efficient mechanism to answer user requirements for applications could enhance the grid resource usage, since the new raised possibilities also increase the application requirement spectrum. This paper describes an extensible semantic grid knowledge base (KB) and a prototypical matching that explores the KB, enhancing the grid content and the grid resource usage.