Abstract The general purpose of this study is to describe and explain attitudes and intention to consume a new fish product by using the general framework from the theory of planned behaviour (TPB) in a multi-group context. The field experiments were performed in Norway with 110 adolescents and young adults and 149 of their parents, and in Spain with 175 adolescents and young adults (termed “young consumers”). The product is a fish burger produced by a Norwegian firm for the Norwegian market, and was tested in-home in both countries. All constructs are analysed by multi-group analysis in LISREL for reliability, validity and invariance across groups. Results from this study indicate that the constructs within the TPB are valid and similar across cultures and generations. The parents showed a significantly higher motivation to consume and more positive attitude toward the fish burger compared with their kids. The Spanish consumers expressed a significantly more negative attitude towards the product compared with the two Norwegian groups. Perceived behavioural control is more important than attitudes and norms in explaining intention to consume the fish burger across cultures (Spain and Norway) and across generations (parents and their kids). This indicates that the TPB can be used not only in explaining intention to consume common food products, but also in the area of testing new products.