We report high‐precision cadmium isotope ratios for a series of standard solutions and geological reference materials for interlaboratory comparison. Complete separation of Cd from a matrix in geological samples was achieved using AG MP‐1M anion exchange resin with > 97.8% recovery. Cadmium isotope ratios were measured by both Neptune plus multi‐collector‐inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) and Nu Plasma II MC‐ICP‐MS at low‐resolution mode. Both sample calibrator bracketing (SSB) and double‐spike techniques (DS) were utilised for mass bias correction. Cadmium isotope ratio data of standard solutions (BAM I012 Cd, SPEX Cd, Alfa Aesar Cd, GSB Cd) and geological reference materials (GSS‐1, GXR‐1, GXR‐2, GSD‐12, NIST SRM 2711a) are reported relative to Cd solution (NIST SRM 3108). The intermediate precision over a three‐year period was better than ± 0.09‰ (2s) for δ114Cd/110Cd and ± 0.06‰ (2s) for δ112Cd/110Cd ratios. SPEX Cd was used as a secondary reference material for Cd isotopic measurement with a δ114/110CdNIST SRM 3108 value of −2.13 ± 0.09‰ (2s). The soil reference material NIST SRM 2711a has a significantly heavier isotopic composition than other soil materials, GXR‐1, GXR‐2 and GSS‐1. New recommended values are presented for future interlaboratory calibration.

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