Display omitted •5-Hydroxymethylfurfural (5-HMF) was investigated in tomato-based sauces.•Approximately 20 % of the samples showed 5-HMF levels above 40 mg kg−1.•5-HMF content was positively and significantly correlated with sugars and acidity.•The proposed method showed an analytical throughput of 26 samples/hour.•The proposed method is in accordance with the principles of green chemistry. 5-Hydroxymethylfurfural (5-HMF) is a compound formed in carbohydrate-containing foods during thermal processing, especially under acidic conditions, and when in high levels it can cause damage to the health of the consumer. In this context, this work aimed to determine 5-HMF using green and validated method by capillary electrophoresis, as well as to analyze sugars (fructose, glucose, and sucrose), pH, and titratable acidity in tomato sauce, ketchup, and tomato paste. 5-HMF separation was performed with short-end injection (-50 mbar/3 s), separation voltage +30 kV, background electrolyte composed by 5 mmol L−1 sodium tetraborate and 120 mmol L−1 sodium dodecyl sulphate (pH 9.3), and direct detection at 284 nm. The results showed that the validation parameters evaluated (linearity, matrix effect, precision, and recovery) were satisfactory, and the method was characterized as excellent according to the green chemistry principles. The content of 5-HMF in the 23 tomato-based products analyzed ranged from 1.30 to 312 mg kg−1, which was positively and significantly correlated with sugars (fructose and glucose) levels and acidity. This study highlights the importance of monitoring of 5-HMF in tomato-based products, as well as the need for establishing maximum legal limits to offer a safe product to the consumer.