Structural Knowledge Graph Navigator (SKGN) supports end users of Web applications by simple means for ad hoc querying and browsing in an object-oriented database. The interface has been implemented within the European project ICONS. SKGN utilizes three core concepts: intentional navigation (in a schema graph), extensional navigation (in an object graph) and annotated user baskets for storing intermediate and final results of querying. SKGN is organized as an applet on the client side and a wrapper to a database on the server side. The paper describes the main ideas of SKGN. Key Words graphical query interface, information browsing, intentional navigation, extensional navigation