This dataset is used in "Avoiding 3D obstacles in mixed reality: Does it differ from negotiating real obstacles?". Mixed-reality technologies are evolving rapidly, allowing for gradually more realistic interaction with digital content while moving freely in real-world environments. In this study, we examined the suitability of the Microsoft HoloLens mixed-reality headset for creating locomotor interactions in real-world environments enriched with 3D holographic obstacles. In Experiment 1, we compared obstacle-avoidance maneuvers of 12 participants stepping over either real or holographic obstacles of different heights and depths. Participants’ avoidance maneuvers were recorded with three spatially and temporally integrated Kinect v2 sensors. Similar to real obstacles, holographic obstacles elicited obstacle-avoidance maneuvers that scaled with obstacle dimensions. However, some participants showed maladaptive obstacle-avoidance maneuvers to holographic obstacles by consistently failing to raise their trail foot or by crossing the obstacle with extreme margins. In Experiment 2, we examined the efficacy of mixed-reality video feedback in altering such maladaptive avoidance maneuvers. Participants quickly adjusted maladaptive maneuvers in the course of mixed-reality feedback trials and these improvements were largely retained in subsequent trials without feedback. Participant-specific differences in real and holographic obstacle avoidance notwithstanding, the present results suggest that 3D holographic obstacles, supplemented with mixed-reality feedback, may be used for studying and perhaps also training 3D obstacle avoidance.