Thermosensitivity of ion channels is a prerequisite for the perception of internal and external temperatures. In mammals, it is critical for the homeostasis of the body temperature, the avoidance of extreme temperatures and survival. In accordance, previous studies revealed an expression of the thermosensitive members of the two-pore K+ channel (K2P) family in tissues important for temperature sensation (e.g. DRG neurons, hypothalamus). Here, we investigated the thermosensitivty of different members of the K2P family (TREK-1, TREK-2, TRAAK, TALK-2; TRESK). While TREK-1 and TREK-2 were strongly activated by elevating temperatures all other K2P channels showed only modest sensitivity with Q10 values around 2. For the TREK channels we observed a clear temperature-optimum. However, this optimum was depending on the heating speed. Slow heating (<0.1°C/s) of the cells resulted in maximal currents at 37°C while a faster heating (>0.2°C/s) resulted in maximal currents at higher temperatures. This observation suggests that the temperature-sensitivity is not an intrinsic feature of the ion channels themselves but rather depends on another regulatory factor. TRAAK channels were previously described as being also temperature-activated. However, in our investigations, these channels were not temperature-activated. Furthermore, chimeras of TREK-1 channels with the C-terminus of TRAAK were not temperature-activated anymore. Vice-versa TRAAK channels with the C-terminus of TREK-1 became thermosensitive. By gradually truncating the C-terminus of TREK-1 channels we identified an 18 amino acid stretch as being essential for the thermosensitivity. Interestingly, the previously identified PKA phosphorylation site (S348) is located within this sequence. The activation of PKA with forskolin/IBMX led to a strong reduction of the basal ion current and further to a complete loss of thermosensivity. As expected, mutating the S348 to A (mimicking a dephosphorylated state) yielded channels with high basal activity and mutating the serine to D (mimicking the phosphorylated state) reduced the basal activity significantly. However, while S348A still was temperature-activated, S348D was not. This observation stays in agreement to the current postulation that TREK-1 channels are opened by the elevation of their C-terminus to the plasma membrane. Consequently, the introduction of the negative charge in S348D provokes channel closure due to a disrupted contact to the plasma membrane. However, the observed temperature-sensitivity of S348A points to a more indirect involvement of the PKA site in temperature perception, as S348A could neither be phosphorylated nor dephosphorylated. Together with the observation that TREK-1 channel activation by temperature depends on the heating speed this may indicate that an additional factor binds to the dephosphorylated S348 to determine the thermosensitivity.