An epoxy composition for applications such as one-part adhesives, coatings, prepreg and molding compounds that includes leuco dyes, particularly those comprising a N,N-dialkylamino-, N,N-diarylamino-, N-alkyl-N-arylamino-, N-alkylamino- or N-arylamino- functional group on one of the aromatic rings, as a co- catalyst or co-curing agent. The use of the leuco dye co-catalyst provides improved curing speed of the epoxy composition comprising a latent curing agent / catalyst such as imidazole microcapsules while maintaining the shelf-life stability. The epoxy may also include a secondary co-catalyst that includes a urea, particularly those comprising a N,N-dialkylamino-, N,N-diarylamino-, N-alkyl-N-arylamino- or dicycloalkylamino- functional group. Secondary cocatalysts of low mobility at the storage conditions are particularly preferred. The improved epoxy composition is implemented as adhesives for manufacturing an anisotropic conductive film (ACF) and also for connecting, encapsulating, or packaging of electronic devices.