The purpose of the study is to explore the possibility to use the experimental prototyping technique called Wizard of Oz as a requirements engineering technique in multimedia development with a focus on how to capture (and test) requirements for system responses in on-going GUI dialogues between user and system. The Wizard-of-Oz technique makes it possible to try interactive prototypes with users or in the development team without needing any programming to be conducted first. In a tourism context interactive prototypes made in the Wizard-of-Oz system called Ozlab were used to produce live answers to tourists. The prototyped information kiosk was offered as a complement to the already running tourist information website. The available surveys and web statistics regarding tourist information system could not provide non-functional requirements. Instead, three interviews and one observation were conducted, leading up to the four experiments where the WOz technique was tried as a requirements engineering technique in addition to the traditional data collection methods. The results of this study show how a graphical Wizard-of-Oz tool can be used as a complement to traditional requirements elicitation methods. The study also shows limitations to WOz based requirements engineering work; subject experts are needed in the wizard team, for example. The study also resulted in several developments of the experimental tool itself; the web feature was exploited much further than originally conceived by the Ozlab developers.