The organic chemistry of nitrosamines is well developed with regard to their syntheses, their structures, and their reactions. They usually are produced by the reaction of nitrous acid () and secondary amines, although other nitrosyl sources (e.g. , , RONO) have the same effect:
The nitrous acid usually arises from protonation of a nitrite. This synthesis method is relevant to the generation of nitrosamines under some biological conditions.  The nitrosation is also partially reversible; aryl nitrosamines rearrange to give a para-nitroso aryl amine in the Fischer-Hepp rearrangement.  
With regards to structure, the  core of nitrosamines is planar, as established by X-ray crystallography. The N-N and N-O distances are 132 and 126 pm, respectively in dimethylnitrosamine, one of the simplest members of a large class of N-nitrosamines
Nitrosamines are not directly carcinogenic. Metabolic activation is required to convert them to the alkylating agents that modify bases in DNA, inducing mutations. The specific alkylating agents vary with the nitrosamine, but all are proposed to feature alkyldiazonium centers.