Co-landfilling of incineration ash and cellulose might facilitate the alkaline degradation of cellulose. A major degradation product is isosaccharinic acid (ISA), a complexing agent for metals. The impact of ISA on the mobility of Pb, Zn, Cr, Cu and Cd from a municipal solid waste incineration dry scrubber residue was studied at laboratory using a reduced 2(5-1) factorial design. Factors investigated were the amount of calcium isosaccharinate (Ca(ISA)2), LIS ratio, temperature, contact time and type of atmosphere (N-2, air, O-2). The effects of pH and Ca(ISA)(2) as well as other factors on the leaching of metals were quantified and modelled using multiple linear regression (alpha = 0.05). Cd was excluded from the study since the concentrations were below the detection limit. The presence of Ca(ISA)(2) resulted in a higher leaching of Cu indicating complex formation. Ca(ISA)2 alone had no effect on the leaching of Pb, Zn and Cr. A secondary effect on the mobilization was predicted to occur since Ca(ISA)(2) had a positive effect on the PH and the leaching of Pb, Zn and Cr increased with increasing PH. The leaching of Ph varied from 24 up to 66 wt.% of the total Ph amount (1.74 +/- 0.02 g(kg TS)(-1)) in the dry scrubber residue. The corresponding interval for Zn (7.29 +/- 0.07 g(kg TS)(-1)) and Cu (0.50 +/- 0.02 g(kg TS)(-1)) were 0.5-14 wt.% of Zn and 0.8-70 wt.% of Cu. Maximum leaching of Cr (0.23 +/- 0.03 g(kg TS)(-1)) was 4.0 wt.%. At conditions similar to a compacted and covered landfill (4 degrees C, 7 days, 0 vol.% O-2) the presence of ISA can increase the leaching of Cu from 2 to 46 wt.% if the amount of cellulose-based waste increases 20 times, from the ratio 1:100 to 1:5. As well, the leaching of Ph, Zn, and Cr can increase from 32 to 54 wt.% (Pb), 0.8-8.0 wt.% (Zn), and 0.5 to 4.0 wt.% (Cr) depending on the amount of cellulose and LIS ratio and PH value. Therefore, a risk (alpha = 0.05) exists that higher amounts of metals are leached from landfills where cellulose-containing waste and ash are co-disposed. This corresponds to an additional 29t of Pb and 17t of Cu leached annually from a compacted and covered landfill in the north of Sweden. (C) 2006 Elsevier B.V. All rights reserved.