The present invention provides curable compositions comprising non-tin metal accelerators that accelerate the condensation curing of moisture-curable silicones/non-silicones. In particular, the present invention provides an accelerator comprising guanidine-containing compounds that are particularly suitable as replacements for organotin in sealant and RTV formulations. Further, the compositions employing a guanidine-containing compound is comparable or superior to organotin such as DBTDL, exhibits certain behavior in the presence of components that allow for tuning or adjusting the cure characteristics of the compositions, and provides good adhesion and storage stability.