The present investigation was conducted to estimate General and Specific Combining Ability Effects in Onion (Allium cepa L.) among 36 genotypes of onion for foueteen characters comprised of bulb yield and its contributing characters. These genotypes were planted in Randomized Block Design with three replications during Rabi season,2022-23 at SKN College of Agriculture, Jobner. The pooled analysis of variance revealed that genotype, environment and genotype × environment interaction were significant for all the characters. The environment wise combining ability analysis revealed significant differences for GCA and SCA variances for all the characters indicating importance of both additive and non-additive gene effects in the genetic control of all the characters studied. The GCA/SCA showed preponderance of non-additive gene action for most of the characters. As regards general combining ability effects and per se performance the parents RO-1, RO-59 and Pusa Madhavi emerged as good general combiner for yield and most of the contributing characters. Out of 28 crosses studied RO-1 × RO-59, RO-1 × Pusa Shobha, RO-1 × Pusa Madhavi, Pusa Madhavi × Pusa Red, Pusa Shobha × Pusa Red and RO-1 × Pusa Red had high per se performance, SCA effects and significant heterotic effect in desirable direction for yield and most of the associated traits. The cross combinations with high SCA effects involving good × good general combiners were identified. All these crosses offer good promise for improvement of respective component characters in specific environment and ultimately bulb yield..