244 Pu (T 1/2 = 81 My) is the longest-lived, most minor, and the most understudied Pu isotope. The anthropogenic production of 244 Pu is linked to nuclear detonations. Reported 244 Pu/ 239 Pu atom ratios in environmental samples range from below 10 -6 to above 10 -3 . This work discusses the performance of the 1 MV Accelerator Mass Spectrometry system at the Centro Nacional de Aceleradores (CNA, Seville, Spain) to analyse 244 Pu at environmental levels. The presence of 232 Th traces in the Pu sample limits the sensitivity of the technique through the formation of the diatomic trication ( 232 Th 12 C) 3+ , of mass 244 u, which must be suppressed by adjusting the stripper gas pressure. A 244 Pu background of 0.0075 fg (2 × 10 4 at) is demonstrated for samples that have undergone a chemical treatment. The reliability of the technique is proved through the analysis of three reference sediments provided by the International Atomic Energy Agency (IAEA-412, IAEA-465, IAEA-385). 244 Pu results are complemented with 239 Pu, 240 Pu, 241 Pu and 236 U and their relative isotopic abundances are discussed.