Palladium-substituted Bacteriochlorophyll derivatives of formula (I), wherein A represents OH, OR1, -O-(CH2)n-Y, -S-(CH2)n-Y, -NH-(CH2)n-Y, -O-(CH2)2-NH2, -O-(CH2)2-OH, -NH-(CH2)n-+N o, X-, -NH0(CH2)2-NH=BOC or -N-(CH2-CH=CH2)2; wherein R1 represents Na+, K+, (Ca2+)0, 5, (Mg2+)0, 5, Li+, NH4+, NH3-C(CH2OH)3 +NH3-CH2-(CHOH)4-CH2OH, +NH2(CH3)-CH2-(CHOH)4-CH2OH or +N(CN'H2n'+1)4; R2 represents H, OH or COOR4, wherein R4 is C1-C12 alkyl or C3-C12 cycloalkl; R3 represents H, OH or C1-C12 alkyl or alkoxy; n is 1, 2, 3, 4, 5 or 6, Y is -NR'1R'2R'3, X-wherein R'1, R'2 and R'3 independently from each other represent -CH3 or -C2H5; X is F, Cl, Br or 1, n' is 1, 2, 3 or 4 and their oxidized forms, are usefu