The accelerator mass spectrometry (AMS) center at Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, Bucharest, is based on the latest-generation 1 MV Tandetron® accelerator, produced by High Voltage Engineering Europa (HVEE), The Netherlands. The AMS center became fully functional at the start of 2013, and at the end of 2015 the laboratory established the RoAMS international code and it was added to the list of AMS laboratories maintained by Radiocarbon journal. An important aspect in the establishment of a new AMS laboratory is the declaration and documentation of the adopted protocols and to demonstrate the reliability and reproducibility of the measurements in comparison to internationally recognized reference materials. In this paper, we present the dating results on the Sixth International Radiocarbon Intercomparison (SIRI) samples that were pretreated, graphitized, and measured in our laboratory. The newly developed sample preparation laboratory can handle sample materials as (1) organic materials, (2) wood, (3) bones, and (4) carbonates. The results of our measurements are in very good agreement with the SIRI consensus values and confirm the reliability of our sample preparation laboratory and also the good performance of the HVEE AMS system. The blank levels for the SIRI materials are 0.277±0.045/0.333±0.046 percent modern carbon (pMC) for wood samples, 0.441±0.038 pMC for bone collagen, and 0.239±0.030 pMC for carbonate materials, considering an average mass of 1 mg sample graphite.