Data comprises IODP Site U1385 Mg/Ca, Fe/Ca and Mn/Ca ratios measured on infaunal benthic foraminifera Uvigerina peregrina and Globobulimina affinis, along with paired (same sample) oxygen isotope ratios, determined using inductively coupled plasma-optical emission spectrophotometry (ICP-OES) and mass spectrometry in the Godwin Laboratory for Palaeoclimate Research, University of Cambridge. The combined records extend back to ~1.45 Ma, spanning marine isotope stages (MIS) 1–47 and have a mean sampling frequency ~1820 yrs. except for two intervals over MIS 27–21 (~980–860 ka) and MIS 40–37 (~1300–1240 ka; (Birner et al., 2016)) where it increases to ~360 yrs. and ~450 yrs. respectively. Mg/Ca determinations on 47 pairs of duplicate samples provide a pooled standard deviation of 0.092 mmol mol-1 with an overall mean precision of 8.2% r.s.d.. Paired Mg/Ca–δ18O records are used to deconvolve benthic δ18O into its deep-water temperature and δ18Oseawater components. All Mg/Ca ratios were corrected by applying a Mg/Mn ratio value of 0.32 mmol mol-1 to account for the potential presence of authigenic Mn-Fe-oxide coatings on sample foraminiferal calcite (de Lange, van Os and Poorter, 1992; Hasenfratz et al., 2017). δ18O values for Cibicidoides wuellerstorfi and Globobulimina affinis were corrected to Uvigerina by the respective offsets of +0.64 and -0.3 ‰ after Shackleton et al. (2000). Data are referenced to the LR04 stack (Lisiecki and Raymo, 2005) on the age model of Hodell et al. (2023). Site U1385 PSU Solver (Thirumalai, Quinn and Marino, 2016) deep-water temperature and δ18Oseawater reconstructions and their propagated errors for the past 1.5 Myr are combined over the most recent 0–50 kyr interval with MD01-2444 (Skinner and Elderfield, 2007) and MD99-2334 which is offset by a temperature of +0.6°C and δ18Oseawater +0.15‰ to account for its deeper setting (Skinner, Shackleton and Elderfield, 2003). Iberian Margin deep-water (>2500m) benthic δ18O, temperature and δ18Oseawater are referenced to the LR04 timescale as above. Stacked deep-water (>2500m) deconvolved benthic Mg/Ca–δ18O records spanning the past 1.5 Myr for: the North Atlantic comprising IODP Site U1385 [Uvigerina peregrina and Globobulimina affinis] and DSDP Site 607 [Cibicidoides wuellerstorfi, Oridorsalis umbonatus, and Uvigerina spp.] (Sosdian and Rosenthal, 2009; Ford et al., 2016); the Pacific incorporating ODP Sites 1123 [Uvigerina spp.] (Elderfield et al., 2012) and Site 1208 [Uvigerina spp.] (Ford and Raymo, 2020); and, Global oceans including all of the above plus ODP Site 1094 [Melonis pompilioides] (Hasenfratz et al., 2019). To investigate changes in abyssal ocean density stratification across the Middle Pleistocene Transition estimates of deep-water temperature and δ18Oseawater were generated with error propagation using PSU Solver in MATLAB (Thirumalai, Quinn and Marino, 2016). PSU Solver-derived δ18O, temperature and δ18Oseawater records for each site were interpolated on a 3 kyr interval and bootstrapped. Stacks were manually created by first identifying gaps in each site's original data and then averaging the means and errors across each age interval.