The objective of the research study was to assess to what extent the processing conditions of modified starches pasting process determined the rheological measurements. Moreover, a conjecture was verified that RVA, a Rapide Visco Analyzer, could be used to determine absolute viscosity values of starch pastes. Six commercially available and chemically modified starches: bleached, oxidized, acetylated, di-starch phosphate, acetylated di-starch phosphate, and acetylated di-starch adipate were pasted in the RVA and Brabender viscographs, and the values of temperature and viscosity were recorded. Immediately after measuring the pasting process parameters, the starch paste was placed in a measuring cylinder of Haake rheometer and the viscosity was measured pursuant to a CR mode at shear rate values ranging from 5 to 600 s^-1. It was found that the process of pasting modified starch depended, primarily, on the profile of temperature changes during the analysis. Additionally, the geometry of measuring system impacts the results ([-] τ to a lesser extent). The rheological properties examined with the use of a device with a defined shear rate (Haake rheometer) depend on the method of preparing the paste, and the gelatinization rate is, here, particularly important. Where a classic, short pasting cycle, like the one in the RVA instrument, is applied, the time duration of preparing a starch solution is too short it contributes to incomplete dissolution of that polymer. Consequently, the viscosity values measured are reported to be underestimated and the variation among the measurements taken to increase. In the case of cross-linked starches, the effect of pasting time on the results obtained is the highest. The measurements taken using the RVA viscograph are not performed under a defined shear rate and they should not be expressed in absolute units (mPa·s) but in conventional RPA units only (Rapide Visco Analyser Units).