Graphical User Interfaces (GUI) can be created using several approaches. Beside using visual editors or a manually written source code, it is possible to employ a declarative method. Such a solution usually allows working on a higher abstraction level which saves the developers‟ time and reduces errors. The approach can follow many ideas. One of them is based on utilizing a Domain Specific Language (DSL). In this paper we present the results of our research concerning a DSL language called GCL (GUI Creating Language). The prototype is implemented as a library for Java with an API emulating the syntax and semantics of a DSL language. A programmer, using a few keywords, is able to create different types of GUIs, including forms, panels, dialogs, etc. The widgets of the GUI are built automatically during the run-time phase based on a given data instance (an ordinary Java object) and optionally are to be customized by the programmer. The main contribution of our work is delivering a working library for a popular platform. The library could be easily ported for other programming languages such the MS C#.