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<p>Uranium–uranium (<span class="inline-formula">²³⁴</span>U–<span class="inline-formula">²³⁸</span>U) disequilibrium dating can determine the age of secondary carbonates over greater time intervals than the well-established <span class="inline-formula">²³⁰</span>Th–<span class="inline-formula">²³⁴</span>U dating method. Yet it is rarely applied due to unknowns in the initial <span class="inline-formula"><i>δ</i>²³⁴</span>U (<span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span>) value, which result in significant age uncertainties. In order to understand the <span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span> in Devils Hole 2 cave, Nevada, we have determined 110 <span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span> values from phreatic calcite using <span class="inline-formula">²³⁰</span>Th–<span class="inline-formula">²³⁴</span>U disequilibrium dating. The sampled calcite was deposited in Devils Hole 2 between 4 and 590 ka, providing a long-term look at <span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span> variability over time. We then performed multi-linear regression among the <span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span> values and correlative <span class="inline-formula"><i>δ</i>¹⁸</span>O and <span class="inline-formula"><i>δ</i>¹³</span>C values. The regression can be used to estimate the <span class="inline-formula"><i>δ</i>²³⁴</span>U<span class="inline-formula">_i</span> value of Devils Hole calcite based upon its measured <span class="inline-formula"><i>δ</i>¹⁸</span>O and <span class="inline-formula"><i>δ</i>¹³</span>C values. Using this approach and the measured present-day <span class="inline-formula"><i>δ</i>²³⁴</span>U values of Devils Hole 2 calcite, we calculated 110 independent <span class="inline-formula">²³⁴</span>U–<span class="inline-formula">²³⁸</span>U ages. In addition, we used newly measured <span class="inline-formula"><i>δ</i>¹⁸</span>O, <span class="inline-formula"><i>δ</i>¹³</span>C, and present-day <span class="inline-formula"><i>δ</i>²³⁴</span>U values to calculate 10 <span class="inline-formula">²³⁴</span>U–<span class="inline-formula">²³⁸</span>U ages that range between 676 and 731 ka, thus allowing us to extend the Devils Hole chronology beyond the <span class="inline-formula">²³⁰</span>Th–<span class="inline-formula">²³⁴</span>U-dated chronology while maintaining an age precision of <span class="inline-formula">∼</span> 2 %. Our results indicate that calcite deposition at Devils Hole 2 cave began no later than 736 <span class="inline-formula">±</span> 11 kyr ago. The novel method presented here may be applied to future speleothem studies in similar hydrogeological settings, given appropriate calibration studies.</p>