Isobutylidenediurea (abbreviated IBDU) is an organic compound with the formula (CH3)2CHCH{NHC(O)NH2}2.

It is a derivative of urea (OC(NH2)2), which itself is highly soluble in water, but IBDU is not.

[1] It is produced by the condensation reaction of isobutyraldehyde and two equivalents of urea: The controlled-release process is the reverse of the above reaction, which only occurs after the IBDU dissolves.

A number of CRF's have been developed based on urea.

Simpler are various urea-formaldehyde materials such as ureaform, which consists of methylene diurea and dimethylene triurea.