Recent research has established cultural background of the users to be an important factor affecting the perception of an interface’s usability. However, the area of cultural customization of speech-based interfaces remains largely unexplored. The present study brings together research from emotion recognition, inter-cultural communication and speech-based interaction and aims at determining differences between expressiveness of participants from Greek and Dutch cultures, dealing with a speech interface customized for their culture. These two cultures differ in their tendency for Uncertainty Avoidance (UA), one of the five cultural dimensions defined by Hofstede. The results show that when encountering errors, members of the culture that ranks higher in the UA scale, i.e. Greeks, are more expressive than those that rank low, i.e. Dutch, especially when encountering errors in a low UA interface. Furthermore, members of the high UA culture prefer the high UA interface over the low UA one.