A process for producing a pyrazoline compound of the formula: ##STR24## wherein R1 and R2 are the same or different and are an alkyl group or combine with the nitrogen atom to form a ring, and X is a pyridyl group, a quinolyl group, or pyridyl or quinolyl group substituted by at least one alkyl or alkoxy group, which comprises reacting a tin complex salt of a hydrazino compound of the formula: X.N