In this paper we report on an empirical study on requirements engineering of hybrid products. Hybrid products (often also referred to as product service systems) – a combination of product, software and service elements – are an emerging trend on the market. Companies intend to offer holistic solutions for customer problems and not single products. The development of hybrid products differs from the development of “classic” products because of the high-level of technological integration of the elements that hybrid products consist of, the interdisciplinarity and the different lifecycles of their single components. We have conducted fifteen expert interviews to explore current practices in requirements engineering in three industries developing hybrid products: automotive, IT-consulting and system integrators, and medical technology. Our results show that most components of hybrid products are developed independently from each other. Based on our empirical insights we have identified requirements and challenges for the design of an integrated requirements engineering process for hybrid products.