Background: Maintenance of thermal homeostasis is of crucial importance in the anesthetized pediatric patient. Gold-standard methods for central core temperature measurement are however inappropriately invasive and impractical in daily practice. The SpotOn sensor uses zero-heat-flux thermometry technology and claims to bypass the invasiveness of classical methods and still accurately display central core temperatures. Up to date no formal analysis of this method in children has taken place. Aims: The primary objective was to assess the accuracy in comparison with esophageal temperature; the secondary objective concerned the safety of the SpotOn sensor in the pediatric patients. Methods: Fifty-four children aged 1-12 years with an American Society of Anesthesiology classification I or II scheduled to undergo elective surgical procedures under general anesthesia for a minimum of 30 minutes were included. Exclusion criteria included: fragile forehead skin, procedures impeding proper SpotOn placement, thoracoscopic or gastroesophageal procedures, coagulopathy, hemodynamic instability, or vasoactive medication use. After sevoflurane induction, an esophageal temperature probe was placed in the lower third of the esophagus, and a SpotOn sensor on the lateral forehead. Temperatures were recorded in pairs per 1 minute intervals. Temperatures were subjected to bias analysis with 0.5°C as the a priori established clinical significance cutoff. Results: Bland-Altman analysis revealed the two methods differed on average 0.14°C (95% limits of agreement: −0.39 to 0.66), with 89.5% of the differences being under 0.5°C. No significant differences could be found between the two methods for the established 0.5°C cutoff. Linear regression analysis determined the following linear regression equation: 0.837x + 5.86 (R 2 = 0.738). Lin's concordance correlation coefficient of 0.83 (95% CI: 0.81-0.84). No complications were observed with the use of the SpotOn sensor. Conclusion: SpotOn revealed itself as accurate as an esophageal temperature probe when estimating central core temperatures under ideal conditions and over a narrow range of temperatures. No adverse effects were observed with the use of the SpotOn sensor.