There is to date abundant evidence about the way openness-performance liaisons are shaped, yet parallel streams of research point towards an intricate relationship between appropriability and openness. Accordingly, while openness may reveal ample opportunities, risks of e.g. misappropriation should also be accounted for in open innovation processes, as they might affect performance. Recent research highlights the scarcity of studies investigating openness, appropriability and performance, and suggests a further need to analyze this in different stages of the innovation process. This study therefore aims to investigate the effects of three groups of intellectual property protection mechanisms (formal, semi-formal and informal) and openness (in terms of collaboration depth with eight types of partners) on two types of innovation performance (efficiency and novelty) across innovation phases. The analysis is based on a sample of 340 manufacturing firms from three European countries. Findings show that in early stages of the innovation process, efficiency is positively linked to the use of semi-formal appropriability mechanisms, such as contracts, yet negatively related to the use of formal ones, such as patents. The latter potentially illustrates the high uncertainty and increased risks of imitation or misappropriation in early innovation phases. Informal appropriability mechanisms contribute to novelty in earlier as well as later stages. Results further indicate novelty is explained by university collaboration throughout the innovation process, while competitor collaboration positively associates with novelty in later innovation stages. Vertical collaborations with supplier and customers reveal contrasting effects, which could also have implications linked to imitation risks. Furthermore, the negative effects of formal appropriability mechanisms and supplier collaboration on innovation performance in distinct stages of the innovation process might have implications for the so-called paradox of disclosure.