Twenty healthy volunteers were recruited for the study. This dataset contains only two subjects (1M,1F, 35y average age) related to the study described below. This dataset contains NIFTI images and data conforms to the BIDS standard. The files can only be accessed by users specified in the permissions and access is restricted for non-commercial use. Licence: CC BY 4.0 - Users must cite the dataset and author's contributions in publications resulting from the use of these data. The study was conducted in accordance with the Declaration of Helsinki and was approved by the local ethics committee. Written informed consent was obtained from each participant. All data were acquired using a Siemens MAGNETOM Prisma (Siemens Healthcare GmbH, Erlangen) 3T clinical scanner with a 32-channel receiver head coil (Siemens Healthcare GmbH, Erlangen). An in-house dual-excitation (Schmithorst et al., 2014) (DEXI) pCASL sequence with two inversion pulses for background suppression was used to collect simultaneous BOLD and ASL data during repeated breath-holding task with breath-holding instructions displayed on the in-bore screen (grey background) and also during rest task with a fixed cross displayed on the in-bore screen. The labelling duration and the Post Label Delay (PLD) were both set to 1.5 s; GRAPPA acceleration (factor = 3) was used with TE1 = 10 ms and TE2 = 30 ms. A TR of 4.4 s was used to acquire 15 2D EPI slices, in-plane resolution 3.4 mm x3.4 mm, and slice thickness 7 mm (20% slice gap). The sequence timings are shown in Figure 3 of Germuska et al. (2019), with BOLD data acquired 1 s after ASL data. The breath-holding protocol consisted of 10 breathholds, each of 20 s duration, with 30 s of recovery in between. Participants were asked to breathe through their nose during the breath-hold task to allow sampling respiratory CO2 and O2 through a nasal cannula using a gas analyser (AEI Technologies, Pittsburgh, PA, USA). Participant were asked to pause and go out from the scanner between the breath-holding protocol and the resting protocol, if needed, providing two separate measurements of OEF and CMRO2. During the first part, the total time for the breath-holding paradigm was 11 minutes 28 s. During the second run, the total time for the resting paradigm was 15 min 08 s. Two calibration images, M0_AP field map image and M0_PA field map image, were acquired for ASL quantification with pCASL and background suppression switched off, with TR of 7 s, and TE = 10 ms. A magnetisation-prepared rapid acquisition with two gradient echo (MP2RAGE) T1-weighted scan was acquired for registration and brain segmentation purposes (matrix 176 x 256 x 256, 1 mm isotropic resolution, TR/TE/ TI1/TI2 = 5000/3.58/700/2500 ms, flip angle1/flip angle2 = 4°/5°). References Chiarelli AM, Germuska M, Chandler H, et al. A flow-diffusion model of oxygen transport for quantitative mapping of cerebral metabolic rate of oxygen (CMRO2) with single gas calibrated fMRI. Journal of Cerebral Blood Flow & Metabolism. 2022;42(7):1192-1209. doi:10.1177/0271678X221077332 Ian D. Driver, Antonio Maria Chiarelli, Hannah L. Chandler, Hannah Thomas, Svetla Manolova, Hanzhang Lu, Richard G. Wise, Michael Germuska; Breath-hold calibrated fMRI mapping of absolute cerebral metabolic rate of oxygen metabolism (CMRO2): An assessment of the accuracy and repeatability in a healthy adult population. Imaging Neuroscience 2024; 2 1–14. doi: https://doi.org/10.1162/imag_a_00298 Germuska, M., Chandler, H. L., Stickland, R. C., Foster, C., Fasano, F., Okell, T. W., Steventon, J., Tomassini, V., Murphy, K., & Wise, R. G. (2019). Dual-calibrated fMRI measurement of absolute cerebral metabolic rate of oxygen consumption and effective oxygen diffusivity. Neuroimage, 184, 717–728. https://doi.org/10.1016/j .neuroimage.2018.09.035 Schmithorst, V. J., Hernandez-Garcia, L., Vannest, J., Rajagopal, A., Lee, G., & Holland, S. K. (2014). Optimized simultaneous ASL and BOLD functional imaging of the whole brain. J Magn Reson Imaging, 39(5), 1104–1117. https://doi.org/10.1002/jmri.24273