This data publication and the related three other datasets contains results from 4 separate experiments aiming to assess the effect of temperature on embryonic and larval development as well as larval swimming in Lophelia pertusa (syn. Desmophyllum pertusum). Parental colonies for subsequent spawning in the laboratory were collected 2019-2020 at the Tisler reef (Lat 58.99, Lon 10.97) 1-3 months before the spawning season for L. pertusa in the Skagerrak (February). Males and females were placed together in laboratory tanks at Tjärnö Marine Laboratory, University of Gothenburg and maintained in flow through of seawater with a salinity around 33 psu and a temperature of 8°C. Corals were fed 2-3 times a week with frozen zooplankton. During the spawning season corals were continuosly observed and when both sexes spawned simultaneously gamets were collected. Gametes were either directly treated with various temperatures or embryo and larvae were maintained at 8°C for a period of time before temperature treatment began. For all experiments, more than one spawn batch was used. For temperature treatments, larvae were moved to 2-3 replicate flasks and placed in thermo regulated cabinets and rooms. This particular dataset shows when the first embryo in any replicate flask in each temperature treatment developed any ciliae.