Expressive behaviour is a vital aspect of human interaction. A model for adaptive emotion expression was developed for the Nao robot. The robot has an internal arousal and va- lence value, which are in uenced by the emotional state of its interaction partner and emotional occurrences such as win- ning a game. It expresses these emotions through its voice, posture, whole body poses, eye colour and gestures. An ex- periment with 18 children (mean age 9) and two Nao robots was conducted to study the in uence of adaptive emotion expression on the interaction behaviour and opinions of chil- dren. In a within-subjects design the children played a quiz with both an a ective robot using the model for adaptive emotion expression and a non-a ective robot without this model. The a ective robot reacted to the emotions of the child using the implementation of the model, the emotions of the child were interpreted by aWizard of Oz. The dependent variables, namely the behaviour and opinions of the children, were measured through video analysis and questionnaires. The results show that children react more expressively and more positively to a robot which adaptively expresses itself than to a robot which does not. The feedback of the children in the questionnaires further suggests that showing emotion through movement is considered a very positive trait for a robot. From their positive reactions we can conclude that children enjoy interacting with a robot which adaptively expresses itself through emotion and gesture more than with a robot which does not do this.