The scientific enterprise depends of the effective transfer of knowledge from creator to user. Recently the rate of scientific knowledge production is overwhelming the ability for researchers to process it. Semantic web technologies may help to handle this vast amount of scientific knowledge. However, automatic computerized techniques that extract semantics from natural language text for use in matching with the request of knowledge seekers achieve only mediocre results. Clearly, semantic descriptions of expert knowledge that are constructed by the knowledge creators themselves will be more accurate. We report an approach and software implementation of a knowledge sharing platform based on semantic web technologies, called EKOSS for expert knowledge ontology-based semantic search, that helps knowledge creator construct semantic descriptions of their knowledge. The EKOSS system enables knowledge creators to construct computer-interpretable semantically rich statements describing their knowledge with minimal effort and without any knowledge of semantic web technologies.