Platinum-based chemotherapy remains standard-of-care for gastric and gastroesophageal junction (GEJ) adenocarcinoma. For locally advanced resectable disease, perioperative treatment with cisplatin-based doublet or triplet chemotherapy regimens had been the predominant approach in Europe and the US, based on pivotal phase III trials including the MAGIC study. Results from more recent landmark studies including the German FLOT4 and the Asian CLASSIC trials have, however, triggered a shift from cisplatin towards oxaliplatin-based chemotherapy protocols in the perioperative setting. Areas covered: This drug profile summarizes current state-of-the-art of perioperative and adjuvant treatment for locally advanced resectable gastric/GEJ cancers with a special focus on the increasingly predominant role of oxaliplatin over cisplatin in this setting. We review pharmacology, clinical efficacy, and safety profile of oxaliplatin and oxaliplatin combination regimens. We highlight recent advances and ongoing developments in the field. Expert opinion: While the adoption of oxaliplatin-containing combination regimens for perioperative therapy of gastric/GEJ cancers represents a significant step ahead, many pivotal questions remain unanswered. At the sample time, the evolution of molecular subtyping and immunotherapy is likely to dramatically change clinical practice in the foreseeable future.