This dataset describes the physiological temperature response of the intertidal macroalga Vaucheria sp. collected from the Wadden Sea near Sylt, Germany. The dataset provides insights into the thermal sensitivity of respiration and photosynthesis in Vaucheria sp. and can be used to assess physiological limits and potential responses of intertidal Vaucheria sp. to warming in temperate coastal ecosystems. Samples were collected in September 2024 from the lower intertidal zone and cultivated for three weeks under controlled laboratory conditions (15 °C, ~100 µmol photons m⁻² s⁻¹, 12:12 h light:dark cycle) before experimentation. The experiment was conducted in October 2024 in climate chambers at six temperature treatments (16, 20, 24, 28, 32, 36 °C). Physiological responses were assessed after 54 h of incubation. Each temperature treatment included four biological replicates. Respiration and net photosynthesis were quantified as oxygen consumption and production using fibre-optic optodes under four irradiance levels (0, 100, 500, 900 µmol photons m⁻² s⁻¹). Oxygen rates were normalised to algal wet weight. Photosynthetic performance was assessed using pulse-amplitude modulated (PAM) fluorometry, including measurements of maximum quantum yield of PSII (Fv/Fm), effective quantum yield (ΦPSII), non-photochemical quenching (NPQ) and rapid light curves.