In<SUB>x</SUB>Al<SUB>1-x</SUB>N material system is a promising candidate for applications in electronic and optoelectronic devices . However, the growth of InAlN by MOCVD system is challenging. One issue is that InAlN is grown at much lower temperature (800~900 °C) than GaN and AlN and Ga atoms can incorporate at the InAlN/AlN interface while the system is cooling down. It has been reported that both the 2DEG density and the mobility are degraded because of the formation of an unexpected GaN layer at the InAlN/AlN interface . In this work, we investigated graded InAlN/AlN/GaN hetero-junctions. Significant charge and mobility enhancements were found by introducing the grading. Conventional (ungraded) and graded samples with different grading lengths were investigated. Two series of samples, one with 2 nm SiN<SUB>x</SUB>/2 nm GaN cap layers on top of InAlN and the other without any caps, were deposited on c-plane sapphire substrate by MOCVD. The growth was initiated with a normal semi-insulating GaN template followed by a thin (~7 Å) AlN interlayer. Graded In<SUB>x</SUB>Al<SUB>1-x</SUB>N layers (x<SUB>In</SUB> from 0 to 18.5%) were deposited afterward using a 2-step temperature ramp with grade thickness of 0 nm, 3 nm, 5 nm, 8 nm, 11 nm, and 14 nm. The growth was continued with the deposition of followed by In<SUB>0.185</SUB>AlN with a thickness of 20 nm to 6 nm, to keep the total thickness of the barrier layer constant (20 nm). For the capped series, a 2 nm GaN and a 2 nm SiN<SUB>x</SUB> were deposited afterwards to address surface effects. The electrical properties were measured by Van der Pauw Hall measurement at room temperature. The 2DEG density (n<SUB>s</SUB>) increased significantly, from 2× 10<SUP>13</SUP> cm<SUP>-2</SUP> (shortest grading 3 nm) to 3× 10<SUP>13</SUP> cm<SUP>-2</SUP> (longest grading 14 nm), compared to n<SUB>s</SUB> without grading, 1.4× 10<SUP>13</SUP> cm<SUP>-2</SUP>. The room temperature mobility (µ) increased from 1100 ± 50 cm<SUP>2</SUP>/Vs (ungraded) to 1300 ± 50 cm<SUP>2</SUP>/Vs for the samples with 3 nm and 5 nm graded lengths. The mobility was around 1000 cm<SUP>2</SUP>/Vs for the sample with 11 nm and 14 nm grades at n<SUB>s</SUB> as high as 3× 10<SUP>13</SUP> cm<SUP>-2</SUP>. With benefits in both charge and mobility, the sheet resistance was remarkably reduced from ~ 400Ω/□ (ungraded) to ~ 200Ω/□ by introducing the grading technology for both, uncapped and capped samples. The surface roughness of the uncapped samples was calculated from 2 µm × 2 µm image taken by AFM, which shows that grading does not degrade the surface morphology (RMS is around 0.6nm). The graded samples were also examined by Atom Probe. No Ga atom peak was present at the InAlN/AlN interface. The accumulation of Ga atoms was suppressed by injecting TMAl and TMIn during cool down to InAlN layer growth temperature.