Color image formation method

A color image formation method comprising:

• overlaying a heat developable color photographic material with a complexing agent sheet via a small amount of water therebetween after or during imagewise exposure,
• wherein the heat developable color photographic material comprises a support having provided thereon at least light-sensitive silver halide grains, a binder, a coupler, a reducing agent and a slightly water-soluble basic metal compound, and the complexing agent-sheet comprising a support having provided thereon at least a complex-forming compound with a metal ion constituting the basic metal compound;
• and heat developing the heat developable color photographic material to obtain a color image thereon,
• wherein the silver halide grains have a silver chloride content of 80 mol % or more, the complexing agent sheet comprises a physical nucleus and a solvent for a silver halide, and the reducing agent is a compound represented by at least one of the formulas (1) to (5):
• ##STR14## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylcarbonamido group, an arylcarbonamido group, an alkylsulfonamido group, an arylsulfonamido group, an alkoxyl group, an aryloxy group, an alkylthio group, an arylthio group, an alkylcarbamoyl group, an arylcarbamoyl group, a carbamoyl group, an alkylsulfamoyl group, an arylsulfamoyl group, a sulfamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl or an acyloxy group;
• R.sub.5 represents an alkyl group, an aryl group or a heterocyclic group;
• Z represents an atomic group for forming an aromatic ring or a heterocyclic aromatic ring, wherein when Z is a benzene ring, the total of Hammett constants (.sigma.) of substituent groups thereof is 1 or more;
• R.sub.6 represents an alkyl group;
• X represents an oxygen atom, a sulfur atom, a selenium atom or an alkyl-substituted or aryl-substituted tertiary nitrogen atom;
• and R.sub.7 and R.sub.8, which may combine together to form a double bond or a ring, each represents a hydrogen atom or a substituent group, wherein the formulas (1) to (5) each contains at least one ballast group having 8 or more carbon atoms in order to impart oil solubility to the molecule thereof.